Of course, one of the other issues is there's no federal Anti-SLAPP statute, and circuits are split as to whether or not state Anti-SLAPP applies to federal lawsuits, so if someone can diversity jurisdiction you into a federal SLAPP lawsuit, you're kind of stuck.
Sounds like a CivPro hypothetical exam question that would give law students nightmares.
You'd better have a slam-dunk of a case if you're going to easily find contingency lawyers. The worst thing you can be is just "too rich" to qualify for pro bono representation... but even then, you still need a slam-dunk case.
I am currently in the process of suing somebody (plaintiff), for the first time in my many decades, and am a semi-retired electrician of average savings... and it is expensive and probably not worth my time but (in theory) hopefully worth it on principle.
So ready for this to be over with; the lawyers will certainly get their$.
So even if the case is clearly being used to strategicly silence you, it'll probably still work (from plaintiff's POV). Same for DMCA.