mountain out of a molehill springs to mind when I first heard about this story.
PLayer has been punished with 3 match ban. The kid should have stuck to the job at hand. You don't see the ball boys at Wimbledon act in this manner. They are trained and disciplined. He had one job to do and failed.
I don't know about AFC Wimbledon, but when the club was Wimbledon FC it would usually take a long time to get the ball back, especially if it went into the stadium (although to be fair if the ball ended up between some seats at Selhurst it wouldn't be anyones fault in particular.)