Last thing I'll say... the back judge, who called the penalty, didn't even turn his head in that direction until the ball was in the end zone and could not possible have seen the PI. Watch him on the gif. He threw the flag "blind" and well after the play was completed. Then they couldn't figure out who to call it on, and now there is retroactive justification that it was "right."
Secondly, the side judge with perfect view of the play calls nothing, and the head ref asks the back judge something to the effect of "are you sure you want to call that?" in the conference.
Third, you can't make a case that there was offensive PI and not also make the case that there was defensive holding. So I don't buy the retroactive "but it was the right call crap" because you also missed a call if that was the case.
Finally, neither of the DBs tries to cover Robinson. Neither of them get "picked." They both actively try to jam the receivers which is why there is the contact. They are initiating it. And then they realize there is busted coverage at the last second and try to fight off the jam that they, the DBs, initiated. I feel like everyone arguing that call is correct completely ignore the fact that the DBs are not even attempting to cover Robinson until the ball is over halfway to him, and the receivers at no point "deviate" from their initial route to impede them.