It's called "a chilling effect".
Furthermore, Ballmer was, and still is, FUDding all the time about Microsoft going to enforce patents that Linux infringes (though not name anything). Even though no action was taken, it also has a chilling effect.
Your defense is acceptable for google. Microsoft deserves to be patent trolled.
My suspicion is that it was just a rogue employee who frankly probably wouldn't have had support from legal, since legal at these organizations tend to be more strategic than tactical (they don't care about one-off infringers, but are usually pushing a bigger strategic story, where patents infringement is just part of it).
http://www.advogato.org/article/101.html
A far cry, I think, from a patent troll takedown.
Microsoft has also directly sued for software patent infringement. (TomTom got sued for using Fat32, presumably for refusing to pay Microsoft's "Linux tax".)
Now they have them and don't like them?
Well, I hope the "troll" wins, maybe the big ones then start lobbying against "patents on ideas".