Just because someone is selling msdn key for bitcoin doesnt means that bitcoin will be rejected by microsoft, do you think that if someone sells it for USD, then microsoft will be rejecting USD?
Bitcoin is tiny - and digital currency - not legal tender, if they are seeing a community working against them (it's not like OP is the only one selling keys) they could stop it. If someone sells it for USD the government behind the USD will force them to stop doing it.