It's an absolutely ancient gag. The dinosaurs went extinct because they died laughing at that one. Presumably he had to add the 2 to the username because he wasn't even the first one to use it here.
And of course he doesn't know what the trans community's preferred terms are because he isn't interested in transgenderism, he's interested in misogyny and he's noticed, correctly, that if he latches on to this ideology he can scold women and deny their rights while flattering himself that he's incredibly progressive and clever. Look at how clever he thought he was, shoehorning in UR MANSPLAINING like we were somehow being hoisted by our own petard.
And as ever, all he's doing is proving that he knows who the women are. From his prehistoric oral sex reference to his low energy argument by assertion to his pathetic belief that he has somehow inverted our arguments against us by accusing us of MANSPLAINING, that's what it all shows. He knows who the women are. Everyone does.