Perhaps I am misunderstanding what PZ is saying here, and if so please correct me, but this sounds an awful lot like a desire to purge the skeptical movement of those with a differing political outlook. I find it hard to see how this would be a good thing.
A small point about your bone of contention with PZ. 1. His quote identified a very specific type of libertarian that espoused the ideas of Ron Paul. As you probably already know many of Paul’s ideas are in opposition to core skeptical values. He is a creationist who supports the government only funding specifically Christian based charities. I know that there are several flavors of libertarians even ones who support some form of limited government. However, mainstream libertarians as defined by their political party’s platform assign agency to the free market to correct society’s inequities without regulation. These sorts of claims are skeptical fair game because they are making some sort of truth claim.
2. I didn’t read his comment as a call to purge Paulites. He said that the discussion itself particularly if you challenge a prominent Paulite speaker would result in a backlash from their supporters that would result in them decamping from the movement. I don’t necessarily agree about that being a good thing. I do however wish that these differences could be discussed and debated openly and rationally within our movement.
I really do wish that there was a real time dialogue rather than encampment and exchanging volleys. Evidently, there is way too much discussion of purges going on somewhere.