There is actually a third scenario that ends the throw in, and it directly relates to this. If instead of tying the ball up, the team B player simply pulls the ball away from the offense, then he has gained possession and the throw in has subsequent ended. The ball was not thrown in bounds, nor did the offense violate.
A related question, can the thrower in reach the ball across the in bound plane, and hand the ball off to a teammate just over the line? My immediate thought is no, and I think I could probably support that with the rules, but why is a defender allowed to grab the ball in that same scenario legally and play on? Shouldn't the same rules apply to both teams here?
|