Of course when you label someone a crank or pseudoscientist, there's always a chance that you make a mistake and end up not learning something that you could have learned, but that's just a trade-off that has to be made, and I see no evidence or argument to suggest that the boycotters have set their bar too low.

I tend to agree. There is a trade off involved in accepting status games and power plays instead of reason. But the downsides don't tend to come with the dramatic boycott situations. The mistakes that lose the learning are most likely to be on the positions that are simply unrewarded and marginalized, not those that must be boycotted to prove your loyalty to Science.