Tritium is a hazard only if taken inside body (say, by drinking it for some hard to imagine reason) and I frankly don't see why it is much of an effort to re-fresh it.
Anyhow, number of strategic warheads have also been reduced a lot by START I and START II treaties (from 10k to about 3-4k total, most of them are placed on ICBMs, about 800 are for strategic bombers) and Russia, by no means a rich country but not poor either could certainly afford to continue to routinely re-fresh its strategic thermonuclear arsenal.
ICBMs, however, are really expensive to produce (most need their fuel refreshed from time to time, by the way, but that's nothing compared to replacing entire missile). Russia could not afford to keep them up in good shape, as far as I know. "Bulava" program that was supposed to produce universal "can be launched from anywhere" missile (NATO calls it SS-NX-30), seeking to re-fresh outdated submarine arsenal; But there was a streakof problems, 49 were produced so far, 24 used for tests, out of 24 test launches only 15 were successful. and that despite rather modest specs, at least on paper, Chinese JL-2 looks much more impressive.
I can't tell if you just don't get it, or you're trolling.
Tritium is a Proton with two Neutrons. It's an isotope of hydrogen. The dangerous part, inside a nuclear device, isn't the tritium. The dangerous part is the Plutonium which is constantly undergoing gamma decay. To suggest that it's safe or easy to replace the tritium, because you could drink it, it just stupid. Getting to the Tritium requires cutting through the protective casing, then the shielding, and all the while worrying about radiation exposure and insanely delicate equipment. Tritium can happily be stored as a gas, and is much easier to deal with when those big pesky oxygen atoms can't act as a damper to decay.
You are obviously trying to equate this to heavy water, one or two tritium or deuterium atoms bonded to an oxygen atom. Yes, you're more than safe to drink that. The results aren't exactly scientific, but estimates place the average human being able to consume multiple kilograms of heavy water without issues, because our body doesn't store water. This is why other nuclear materials are devastating in small quantities (if memory serves, strontium replaces calcium in bones). Likewise, some decay can be blocked relatively easily. For instance, the alpha decay of depleted uranium can effectively be blocked by a layer of paper. This is why your average tank operator isn't in a hazmat suit, despite being surrounded by a radioactive material.
As far as fission, you need to be aware of the idea of critical mass. Basically, you've got to capture the energy from a decaying particle, and use it to decay another particle. With extremely heavy particles you'll either need to artificially induce this by kinetic compression, or have a material that decays rapidly and has a lot of daughter particles after decay. In the case of a nuke, you want your radioactive elements as far away from a critical mass as possible (for storage), so they don't go off unexpectedly. Hence, you need some initial source of energy and particles to allow you to reach a critical mass. Tritium is this primer. The hydrogen atom has a very small half-life, and given its small mass it's easy to get going. I used the thermite example earlier because it's the same idea. Getting an energy source to start the process is difficult, so people use phosphorous or magnesium to start it. Both of those materials are relatively easy to start oxidizing (read: fire), which releases enough energy to start the thermolytic reaction.
Replacing the tritium is necessary to have an active nuke. If you don't, and the reaction doesn't reach critical mass, instead of a nuclear explosion you've got a dirty bomb. Sadly enough, the powderized and ejected nuclear material might be just as deadly, long term, as the nuclear blast. The problem is that dying from cancers and radiation poisoning is...there are no words. The best I can offer is inhumanly monsterous.
I will broach the subject of ICBM maintenance. It's costly, but it's money that we are obliged to spend because our military budget, in the US, is largely controlled by politicians. Politicians take tax money, and divide it up so as to best benefit their constituents. How does all of that relate to ICBMs? It's simple; maintaining them, without ever firing one off, is a source of cash.
Rocket fuel is neither cheap, nor readily accessible. Both of these factors make it a gold mine in the private sector. Businesses, like heat treaters, can use the fuel near end of life. Machine shops are paid to provide replacement components, which creates jobs. Facilities staffing, as well as logistics for the ICBM site, mean even more jobs. In all honesty, if every ICBM disintegrated tomorrow it'd devastate local economies.
You've talked about a mobile missile platform, but that's largely a joke without a punchline. When it comes to a mobile platform you don't want a nuclear device. You've got to find a way to store it safely, which means shielding. Shielding means immense weight. Immense weight means that your mobile nuclear weapon is a giant target. This doesn't even begin to touch on the political ramifications of having a mobile war crime. If you'd searched anything but wikipedia (I say that because you use their exact wording about the testing), you'd understand that these mobile weapons platforms aren't frightening because of their relatively low yield nukes. The reason these mobile platforms are frightening is their ability to launch an attack with functionally zero warning. If an ICBM was launched the intended target would know about it well in advance of arrival. They might now be able to do anything about it, but you can always respond to an ICBM with your own. A missile, launched without any acknowledgement, from a platform that could not be found afterwards, is a political nightmare. You have to find whom to blame, you have to formulate a response, and you have to keep your people calm despite having no information. A nuke is frightening, but a sneak attack from an unknown assailant only using conventional weapons is infinitely worse.
There is also the other problem. There are relatively few people who have the technology to make fissile material, and fewer who have developed weapons with it. If you were to use a nuclear weapon the ramifications would be dire. Let's play devil's advocate here, and say England was peeved with the US because of our foreign policy...issues. They attacked the Virgin Islands, to send us a message. Within hours we'd be able to trace the technology back to its source. Suddenly, it's not England versus the US. Everybody else on the planet has seen a nuclear attack, and despite the US largely being a-holes (politically), we're the victims to the international community. You've suddenly got sympathy for the devil, because an even bigger devil gave them a black eye. I've used the US and England because the idea is preposterous, but change the players. The US and China are in the same boat. Russia and China have a falling out over resources. The possibility is always there, which is basically why the concept of MAD still propagates today. This is why mobile platforms don't harbor nukes as a primary weapon, and going back to the OP why this bomber is a joke. Nobody in their right mind uses nuclear devices, because even winning the conflict would cost you the war. Hence, the bombers and ICBMs are devices that should never be proven effective. That's the joke without a punchline; the best weapon is the one you never use.
