MS/PF fought. And fought dirty. They got caught. Had they gone to trial they would have lost. They knew that. The only reason they were able to settle for 10mil was SFOR's dire financial position.
Blackberry fought for years with a Tiny co and end up paying $675m for patent infringement. If you are on the wrong side, doesn't matter who you are, MSFT or BBRY or for that matter, Centrify, Trustwave or DUO security.