Is it really that simple?
Ref's don't call every foul because it would wreck the flow of the game. So if there's a tickey-tack foul that doesn't result in a change of possession or otherwise impact things they often let it go. In addition, they are human and make mistakes. If they realize they did, they make a make up call to hopefully even things out, so that the play on the court determines the winner - not them.
In this case, the refs somehow decided that the video evidence was enough to overturn the on court call. To anyone who saw the multiple replays of the out of bounds it was anything but clear cut, despite what the moron announcers were trying to sell. Given the reasonable doubt that must have existed in their heads, the only way to sort of even things out would have been to swallow their whistles and see what happens on the court. Bearcats got the ball, but they don't get the ball and the call.