Opinions on TJ and his relationships
In my opinion, TJ’s behavior towards Buffy does not come from a inherently sexist place. Buffy being girl is not the biggest, or the real reason that TJ is a dick to her. He feels threatened by her, and now that we know he considers himself to be stupid, we know that basketball is the only safe haven for him. It is literally his reputation. At first, it does seem that TJ resentment of Buffy came from a sexist place, but now it seems more personal. While he may start to respect her on the court, it is going to take some time for him to become friends with her.
I know many people here are saying that they will not support a TJ/Cyrus relationship until he has a redemption arc, and that is fine. It is your right to choose that, however, I feel like this show, if it chooses to put the two boys in a romantic relationship, would have their relationship start before or during the redemption arc, not after. Realistically speaking, people are going to be dicks to certain people while being super kind to others because it is human nature, especially when the resentment seems so personal. So, I think that they might use the relationship to help TJ break out of his shell, and help him realize that he doesn’t need to care about his reputation, and slowly but surely grow to be friends with Buffy.
TJ’s redemption arc is going to take time, much like every other meaningful arc on this show, so be patient.