Such treatment of people with whom you disagree is simply disgusting, but in a terrible way it's just laughable. A woman complains about sexism, and men react by being sexist pigs? They need to look at themselves.
I think there are two things at work. Firstly, people - including so-called skeptics - generally hate having anything said against them or having their attitudes brought into question. These men don't like being told that they are sexist, but instead of reacting to it in the civilised way that they pretend to, they react like cruel children.
Secondly, and I notice this very often, people confuse having obscure or unusual opinions for being "skeptical" or being "open-minded". In reality, this is an illusion. Having liberal beliefs, for example, makes you no more open-minded than someone who has conservative ones.
This stems from the fact that at some point a "skeptic" must have thought skeptically about a particular thing - belief in God, for example - and ended up identifying themselves as a skeptical person when, in reality, they just happen to have non-mainstream views about which they are as dogmatic as people who never stray outside the norm. /r/Atheism over on Reddit is a very obvious and salient example of this.
I've actually always thought that Richard Dawkins comes off as an asshole, too.