No software patent troll has even the slightest care about free software, open source, Linux, or whatever. Their goal is to extract money from large, rich corporations with as little outlay and effort on their part; the more the better.
Free software is simply the vector (and, given the nature of how free software works, a very easy vector!) by which they achieve their goals. If anything it is in the best interest of all such trolls that free software stay alive and well.
How much easier could it be to determine if someone is infringing on your patent than to simply download and examine their code? Better yet, now that prior art doesn't guarantee patent invalidation, simply look at some rich corporation's code and file as many patents against it as you can. It's only a matter of time before you'll find an idiotic judge, ignorant jury, or lazy lawyer (or some combination) and suddenly "big evil corporation" owes you a lot of cha-ching!