On topic, not that I defend his action but this is why you don't put your hands on anybody unless you're ready to have their hands put on you.
Regardless, she knew she was at a physical disadvantage to him so why make things physical? Again, I do not approve of Mixon's action because it doesn't excuse it but honestly, her getting punched like that was her fault and I know people don't like to hear that. He was walking away when she started putting her hands on him. If it were me pushing and slapping a guy who clearly could overpower me and I got knocked out most people would have no problem saying that I had it coming.
Do you consider the girl to be a POS thug as well? She's the one who chose to make the altercation a physical one.
For the last time, I do not condone Mixon's use of force. I've never hit a woman (not even my older, bigger sisters when they'd get physical with me as a kid) because I was always taught that a man should never do that. That said, the same person who taught me that also taught my sisters that if they don't want a man (or anyone) hitting them, then keep their hands to themselves, because you never know what kind of person you're dealing with and how they will retaliate. You don't go poking the bear.