http://en.wikipedia.org/wiki/Pussy
I don't think that "pusillaminous" is the origin of pussy, but, more importantly, I don't think that most people who use pussy as an insult have this in mind when they say it. I think it's specifically a criticism of masculinity. Anyway, while that's interesting it's also not my point.
My point is that while some members of some groups are impatient and get angry rather than explaining (I know I'm guilty of it as an atheist!) calmly to yet another person, that it doesn't mean that their argument is invalid. It means they got mad. OR, in Ryking's case, it means that they did explain and he still just mocked them. Check this out:
http://mirkwood.tumblr.com/post/6600362605/alexander-ryking-you-might-be-a-feminazi-if
http://mirkwood.tumblr.com/post/6601256078/just-saw-your-screed-tl-dr-plus-i-saw-you-resorting
Someone responded to every single one of those points. Ryking's response? Flat-out refusing to read it. So... if you want to point out a problem with a specific movement I suggest criticizing that movement yourself, not siding with someone who obviously does not care and just has a grudge.

I see. I’m going to admit, I used to have a grudge against feminists myself and denied all sorts of shit: slut-shaming, priviledge, all of that. But I came to realize I was not being funny. I do consider myself a feminist, however of course I am not perfect. And I do not appreciate anybody, feminist or not, who refuses to listen.