Depends what he's doing there - if its just a motivational/good luck thing, none whatsoever. If he is there to get a feel of the spirit in the team and keep an eye on what AP is doing about such things pre-match, I still dont have a problem. If he is trying to communicate his tactical perspective, I would be outraged, but then I suspect AP would have sent him out with a flea in his ear.
Considering the amount of money invested in the team, absolutely.
Yes, if a "quiet word" hasnt worked, and to be fair, it appears to have made a significant difference.