I'd just go with "consider the source," but you're a good friend, and so here I am.
Mansplaining, without me hitting Google and as I understand it, is when men give their perspective on women's issues. It's why I don't stay with the abortion threads until they expel their last breath. It's ridiculous that a bunch of men are trying to explain why the only logical answer is that the woman either never have sex again, or sign up for that 18 year sentence that just got dropped on her head.
Now, if they understand the concept of women's rights, welcome aboard and pass the ammunition. But if they think that they should be able to dictate ... and etc.You've seen my argument, I don't need to lay the whole thing out here.
As to the being treated as less than by virtue of genitals? Most of the time it's laughable. Some of the time, it's irritating. But when I start publishing, I have a decision to make - and I'm sure everybody knows why J.K. Rowling went with the initials.