This sounds like a stretch. To me, it sounds like the FCC wants to lock down the wireless radios themselves to ensure compliance with FCC laws regarding how radio frequencies can be used and at what frequencies. While I can see this being an excuse to kill open source firmwares (or the OS for routers,) I think it might be a stretch. I see this being a change on the wireless transceivers themselves. So for example, the radio itself would simply prohibit broadcasting frequencies outside the range the FCC has allowed for the device.
So while I can see why person might be concerned, I don't see it as killing open source router software. I do see it as ensuring regulatory compliance of said software though.
Personally, I think it's important that a 2.4Ghz radio, only actually operates at 2.4Ghz. We have to be careful with how we use radio waves as we have to share the medium they travel in (unless talking about something like coaxial cable where radio waves inside are shielded from the outside and vise versa.)