Now, I am an actual high school football official. I do NFHS, not NCAA rules (such as TX), but it is close enough for this discussion.
First, the whistle does not matter with respect to late hits. The mantra “play to the whistle” is not a license to tee off on anyone. The ball is dead either by a player in possession in which any part other than hands or feet are touching the ground, the ball touches anything out of bounds (including any player or official that is out of bounds), or otherwise dead by rule (e.g. touchdown, touchback, etc). The whistle is a safety device that merely announces that fact. Indeeed, a whistle is not required and on some of the more obvious plays (e.g. deep pass incomplete, missed field goal, etc) you may not even hear a whistle.
So, no, the fact that there was no whistle does not give Tago any leeway. I also think he is fortunate not to be ejected. The position of his head and the location of contact are the issues. I think they tried to write out the intent portion of the old rule and make it more black and white.
As for PI, in NFHS, PI is purely a contact foul. A couple of years ago the eliminated face guarding. Now, for there to be PI, there has to be contact. I’m not sure on NCAA, but I think the NFHS rule change was to bring it in line with both NCAA and NFL. The pass being catchable was only a recent addition. So I think NCAA is the same.
Also, with respect to square to the LOS, I thought that was ticky-tacky BS. And I’m not sure they have it right. I’ve been digging through the officiating forums (see refstripes.com) and it’s not coming up. But I fail to see any advantage gained by the twist in his stance, so I don’t get their call. Plus, this isn’t new. The crew should be aware of unusual or trick play, and they should have at least warned WSU. Perhaps they did. But still crappy.
Finally, on the disconcerting signals. I’d like to know what the claimed were the problem. We reserve that for mimicking the snap count or make offensive signals. But calling out coverages, formation strength, etc. should be fine. Even if barked or other strange sounds. I have to reserve judgement on this one, but I doubt this was new, and it wasn’t called all season.