Kill Throw-in

[wfd21]

Had This sit. in 3 person crew, BV, last night. T has throw-in on end line. I am New L. There are numerous subs both sides. C brings in subs. I am counting players. C drops hand. T gives ball to A1. I am still counting players. Throw in released. Ball in air. Clock still stoped. I have 6 players for B team on court. I blow whistle, kill ball before caught, or clock started. B coach realizes 6 players on court pulls closest one to him off. "A" coach wants explanation for whistle. I go over and explain. "A" coach wants to know why I did not let it go and give T to team B. I explained why I killed ball to avoid T. He does not like it. Close game. He wants T given. We go back to "A" throw in with 10 players.
Your thoughts on how I handled situation.