I see your point: if someone is screwing up the political threads, that attitude on their part fairly easily marks them as a political opponent who is playing dirty.
But, see, that's the weird thing about this particular situation. It's been going on for some months now and it often happens on threads which are not overtly political.
A crime thread can become political, in that people may express different views on the death penalty, or on search/seizure, or on police misconduct. The troll I've been noticing (I still believe it's one person, though it has a different name or two for each thread) brings the bleeding-heart liberal cant to the crime threads it disrupts.
And, more to the point you made, it would indeed seem that someone whose politics were 180 degrees removed from FR's would want to stick on the political threads. But maybe some of these left-wingers are being a little more subtle. (I know, subtlety in such people is hard to imagine.)
You're right about the threads dealing with nationally publicized crimes--there will be teaming up, and fighting. But this troll never goes that deep on the issues. It clearly has no actual views on such things, but is only there to disrupt and make a mockery of all discussion.
I don't know the why or wherefore of it yet, but it's a definite phenomenon that is occurring on here over and over lately. That's all I know for sure.