GPL enforcement is now patented?

I don't think the SFLC would likely ever be sued, at least not until after Bilski, and likely only if that ruling was favorable to the patent aggressors or else was full of loopholes.

If I were sued, I would like to be able to fund a trip to the US Supreme Court with hope to strike down all software and many other types of patents based on them not promoting the progress of science and useful arts.

The current patent system (especially as concerns software) makes it easier to go after risk-averse "evil profit-making" businesses rather than "loved" and "poor" nonprofits that might solicit and gain wide backing to be able to take you to the US Supreme Court and win on Constitutionality grounds. I would also avoid suing a group backed by lawyers willing to work for the right cause.

Any FOSS developer passionate about what s/he does and its correctness is not too likely to get attacked directly by smart patent owners, but the aggressors will help marginalize and/or raise costs for FOSS in a way that tends to favor these monopolists.

If software patents were to truly become legitimized, it would be much more beneficial for FOSS project developers to move into the "trolling" business or else make sure that a few such trolls existed to help defend those projects. Focus on patenting ahead of Microsoft, IBM, and others and then use the money to defend/fund the FOSS projects against proxy trolls and other trolls. Soon, this would lead to a change of heart by these giants. Note that prior art is not a bargaining hand. Aggressors and anticompetitive entities will leverage your very ideas to take out broad patents around your invention so that it cannot grow.

Since I like fairness and not wasting time and money in a broken system or having to pull out "guns" instead of living in peace, I try to avoid patent traps that are unnecessary. This includes avoiding patents from FOSS hostile groups *that can easily be avoided*. Eg, I would avoid Microsoft patented APIs, protocols, and formats as much as possible -- improve (GNU/)Linux, but I would not stop working on software that was deemed essential or very useful -- eg, on a Linux system.