LWN, who are generally pretty well-informed on free software matters, have so far reported this only in passing. They do note that the change was released in such a manner as, arguably, to make it likely to be missed; read into that what you will.
Examination of Greg's patch reveals it's not just .ru addresses; some maintainers with gmail addresses were also removed, so this doesn't look like an uninformed snap decision. No public discussion happened beforehand, and Greg's patch (and Linus' followup) contain nothing other than a single sentence about "compliance", so as has been pointed out we can't (yet) know what motivated this.
Linus has since noted that the change was driven by actual legal advice to the maintainers. He won't say what that was, but again, there are grounds for thinking this isn't just some performative stunt.
As for the whole Linux-Foundation-is-controlled-by-the-US-gummint thing, well, it certainly has to obey US laws. But Linus is the guy with final say on what goes into the kernel, not the Foundation, and I don't think the Foundation is so foolish as to assume that their paying him means they get to tell him what to do in that regard. In the limiting case, Linus still has Finnish citizenship, so as an EU national has nearly thirty other countries he could go and live in if the US government decided to get hot and heavy with him.
Edit: since I wrote this, more information has become available. At the time of writing this edit, the latest news is ably summarised by Sanctified Brethren in his/her answer, which I think is well-worth reading.