Grabbing a player

[Man In Blue]

We are 20 seconds into the game and we are shooting a 2 shot free throw. I am the new trail. On the second shot B1 grabs A1's shirt so that he can not get around the box out. Ball goes in.

I called a holding foul. B coach doesn't like it. He feels that because the ball went in it's a dead ball. I told the coach that the ball was live and in the air when the foul happened.

So now a couple of things. I know the ball was live. Would it have mattered if the ball was through the rim when the infraction happened?

Would it have been better to issue a warning because it happened so early in the game? It seemed to be a habit of B1's as later in the game (while shooting free throws) he reached for the shirt of an opposing player and caught himself.