This kind of activism is definitely counterproductive -- but a 'sensible moderate' worthy of the adjective would be aware that there is nastiness and idiocy to

This kind of activism is definitely counterproductive -- but a 'sensible moderate' worthy of the adjective would be aware that there is nastiness and idiocy to be found among the advocates of every position on every issue, and so changing your mind about substantive questions on that basis is just handing your brain over to whoever can dredge up the most egregious examples and bring them to your attention the most efficiently.