Yeah, that's pretty much where I'm at. I don't think taunting should be a penalty at all, but I agree with Mack when he said that if it's going to get flagged then it should be flagged the same for everyone.
At most, I think doing horns down is weird when the team isn't playing Texas (unless its OU - I think horns down might be their official hand signal). The phrase "rent free" gets tossed around too much, but it really is the truth when it comes to Texas. Watching a WVU-ISU game and seeing fans from both teams doing horns down, you have to wonder what's going through those fans' heads? They're at a football game, cheering for their program, interacting with opposing fans, and their first thought is about Texas? A bit sad, tbqh. But the most that gets out of me is a chuckle and shake of the head.
But when it's the fans of the school we're playing? Sure, go nuts. Horns down all you want. Just part of the fun. Most teams (outside the old SWC) don't even have a hand signal.