Note who they WON'T sue
They don't go after anyone that they think will challenge them: not Red Hat, not IBM, not Google, etc... all with far more widespread use of Linux. And more $$ if Microsoft wins.
But they know that when someone takes them to court rather than knuckling under, then they'll have to disclose their patents, and that's the first step to either invalidating them or working around them. Then they lose their FUD which is far more valuable to them than the patents.