I don't think that's what AMD is doing at all. The public knows how serious this is. AMD knows they have nothing to add because, at this moment, there is no real solution for Spectre. Like everyone else, they're working the problem and they're not going to say anything until they have something to say.
There real thing with Meltdown and Spectre is this, there are no villains in this matter. Not one manufacturer in their right mind would engineer such a pervasive problem into their products. And the fact that Spectre affects every CPU in existence for the past 25+ years, regardless of architecture, is evidence enough that it was not foreseen and has caught everyone almost equally off-guard. Laying blame at anyone is a waste of time and effort because we'd have to blame everyone equally. Even old games systems like the Playstation and N64 are vulnerable. So let's all stop the blame game, focus on the details of the problems and solving it, shall we?
Because of the way these vulnerabilities work, they take advantage of a very useful set of functions within CPU's that help them work faster and more efficiently. Engineering that out of CPU's is going to take us back at least a decade, performance-wise, and even more than that for some forms of software. Instead, it might be better to find a way to isolate those functions from direct high-level software access, which would mitigate the problems without removing them.