Again, I agree that it could have been anyone (I think Adobe took part in the recent raid of LG offices [or the authorities made them take part in this] -- http://www.google.com/hostednews/afp/article/ALeqM5gQtvHJ_pY...), but if it were Microsoft's lawyers, Microsoft is fully responsible for their actions.
Well, it gets a little tricky for the reasons you just described. If the 'authorities made' some company's representatives do something, it's not so perfectly clear the company is 'fully responsible' for their actions. It's a huge morass of ethical issues which automatically appears when a company does business in such places. The extremes of the spectrum are not doing business there at all and full-on collusion. Microsoft and I imagine just about all US technology companies in Russia likely fall somewhere in the middle. My point is that the debate about where precisely is not really all that interesting or important.