An attractive man who flirts with or "hits" on a consenting woman isn't "getting away" with harassment, he isn't harassing her in the first place! I think a lot of incels are angry that women have standards of appearance for their potential partners, so they make rage comics and posts about how innocent ugly men are unfairly viewed as creepy for the "same" behaviors as attractive men. I also think at least some of them struggle with more sophisticated social skills (such as body language) or simply don't put any effort into determining if their audience is receptive or interested in them. So they completely skip over how the attractive man might have done plenty of work to assess if he'll be received well before he ever makes a flirty comment.