I think a major problem is that you perceive this as a case of (unaggressively) stating a harmless opinion vs (aggressive) putdown by extremists. I obviously disagree, and I'll try to explain where I'm coming from.
Two short remarks first:
1. "Ignorant" is not an extreme word. It's pretty important to realize one is bound to be ignorant on some issues. I'd say being aware of one's own tendency towards ignorance is probably the most important requirement for resisting bigotry. So if someone claims you're ignorant about something, it's a good idea to take breather and listen first, instead of rejecting it straight away.
2. "Racist" is not an extreme word either, although obviously not every claim of racism is justified.
So here's my take: Central to all of this is that "social justice warrior" is a right wing combat term. It really is. Although still a quite recent one, that term already has a rich and ugly history, which in turn is part of much wider political and social traditions directed against the emancipation of women and social minorities. If you use that term (and no one forces you to do it), you associate yourself with these ongoing traditions, wether you're aware of it or not. And you also set a fairly aggressive tone right away, regardless if intended or not. Both for the purely degoratory nature of that term and its political context. This certainly influences the way the responses turn out. (Although I don't think you were treated unfairly, as you were given the opportunity to substantiate your claim several times.)
Bottom line for me is this: you seem to regard yourself as something between a liberal and conservative, but your unironic use of right wing slang, and taking a myth produced by anti-feminist trolls for the reality of feminism, are indications that anti-liberal ideology is much more normalized in your environment than you're aware of. As a result, these things might seem inoffensive and reasonable, and even liberal to you, but they aren't. And at some point posts have to be judged on their content, not on the stated intentions of the poster.
Finally, if you could see what I write not as unwarranted and abusive, but as an honest criticism of something you might not be aware of enough, there might even be space to talk about it. I refer back to what I've written under 1.