He just has to focus on the backboard and rim and tune out everything else. Its a shot that many players could hit while blindfolded. (That would be an entertaining wrinkle.)

That said, I agree that it does probably have an effect and gives an advantage to the home team. However, free throws are a relatively boring part of the game. Any distractions fans can conceive are entertaining for everyone. Even the opposing players have fun with it sometimes.

For live ball situations it should be banned. Can you imagine trying to take a guarded three point shot while that stuff is happening behind the backboard? LOL