I agree the hit on Tua should have been called, but I have seen this happen many times and I don't think I've ever seen the defensive player called for anything.
Regarding the targeting call, I have to agree it was technically targeting. The argument that he had time to move from defenseless to under control doesn't work, because he was entering the end zone as he caught the ball. If this isn't a bang bang play, then the hit is a late hit, and that should have been called as unnecessary roughness.
What is more, Ruggs doesn't duck. He starts to fall, but he doesn't lower his head, he just starts to drop, and he hasn't moved very far when the hit happened. Ultimately, the defensive player went high, which is the reason for the rule. If he had hit lower in the chest area, there wouldn't be a discussion.
All that being said, I have never liked the ejection part of the rule. It is especially a big deal because of the inconsistency. The D. White hit is a perfect example. In reality it was a minor hit, but it was a textbook example of targeting. Just as he gets there he ducks his head and the crown of his helmet hits the QB in the face. He may have hit with his hands first, but crown of helmet to head of QB is going to get called no matter what. Head up and facemark hits, no call. But it was obvious he was pulling up to some extent, which is what makes this a mess. If the hit hadn't been called for targeting, it wouldn't have rated roughing the passer. That is the part that drives me crazy.