It's fascinating what some people are demanding.

AFAIK (not a lawyer) DMCA requests are presumed correct so the hoster has to take the content down, with a later process to handle a dispute.

Microsoft is a site that hosts projects for free while following the law. They have no interest in defending a project legally (besides, maybe, PR). Why would they?

The request isn't clearly fraudulent, the RIAA's case is shaky, but it's something one could defend in a court and maybe even win with, provided a strong imbalance of money to spend.