Slapping backboard or basket interference

[kld9]

I recently observed a boys varsity game in which player A was on a breakaway layup. Player B in pursuit. After the ball hits the backboard, player B slaps the backboard and causes the ball to roll off the rim. The trail official calls basket interference. The coach of team A wants a technical for slapping the backboard. After the officials discuss, they wave off the basket interference and call the technical. Is this the correct call or could you also count the basket? Thanks.