I agree that Tess was overreacting. And she uses her sexuality as a way to victimize herself so she can get what she wants from her parents.

Like that time Alex came over, and Tess took advantage of Beth wanting to be as accepting as possible to take Alex up to her room and make out with them, knowing full well it was against the rules. And then, when her mother tells her what she did was wrong, she immediately turns the topic to homophobia, saying her mom had "a face". Like of course she did, she was shocked because she trusted you and she caught you doing something you shouldn't. It wasn't about sexuality, it was about finding her kid in bed with someone, regardless of gender, that's upsetting.

Whenever Beth or Randall get mad at her for anything related to dating, she uses homophobia as a shield, guilting her parents into thinking they hurt her feelings and excusing her misbehavior. Because Beth and Deja were right. If Deja doesn't get to have the person she's dating in her room with the door closed, then Tess shouldn't be able to either. Beth didn't want to seem bigoted towards Tess' relationship with Alex in any way, so she never clarified boundaries, and Tess took advantage of that, by breaking a rule that was obvious, and then worse, insulting and manipulating her mom when she tries to enforce it. Regardless of your sexuality, you should be subject to the rules (equality goes both ways, for privilege and responsiblity), and disrespecting your parents isn't okay.