It’s a game, not a war!
Teach your son how to protect the ball and block the steal. Also teach him how to steal. It’s all part of the game. And, it’s only a game.
By teaching him to battle, especially in this situation where he appeared to be the instigator of the fight, teach him diplomacy.
That same boy can become a friend and support your son in tough situations in the future.
Be careful teaching him be be an agressor as he will always meet someone tougher and meaner. Diplomacy from a position of strength is the best thing to teach your son.
Just what I was going to say.
It is part of the game. Accept that.
If you don’t like it don’t play the game or get better.