Thanks for the welcome, JR.
I agree B1 should have been called for the foul.
The tricky part here is "of his own volition".
Is A1 legally out of bounds as a result of contact with B1?
Is A1 allowed to come back on the court and resume the dribble (assuming the ball is never out of bounds).
It seems to be a moot point if a foul should have been called.
I don't think the layup scenario would be relevant, because A1 would not be the first person to touch the ball after a made basket.
Regardless, thanks for the input.
(FYI, I'm a rules buff...something my golf buddies REALLY appreciate.
)