I think there used to be some play where A1, on a breakaway, jumps up, grabs the rim with one hand and, pulls himself up, and dunks with the other hand.
Ruling: T for grabbing the ring. Makes the ball dead. T for dunking.
Not listed in the ruling, the T you'd have to give the coach.
In the OP -- treat it as an "unsporting act" -- if it was, enforce it (much like the slapping the backboard rule). I don't think it was in your case.