I'm going with "It depends how the players react".
This is similar to a foul call when the ball is fair which happened a couple of years ago in MLB. If the defense is affected by the call, then keep R2 at 3B. If they aren't, then let the play go on. Once the umpire influences the game, the participants affected cannot be held accountable for it IMO.
Now, as for how they should have handled it:
1) BU gets a better angle.
2) AC gets sent to the dugout.
3) After calmed and 1 on 1, HC gets explained to that PU has other responsibilities on that play. And, he shouldn't be looking for a bail out on plays with multiple runners especially if one could be scoring. PU may or may not see it.
4) BU goes to short RF and waits for the bottom of the inning.
I accept getting help when needed and the BU got lucky that PU could help. But, he needs to not rely on that and do a better job of getting into position, knowing the situation before asking, and making his calls with no help if possible.