Who is right?

[Feellikefrighteningyeah]

Another anger outburst from Ds(14) last night. Complaining about a parent app on his phone. He has ADHD and I have to turn off apps when it's homework time or when he makes bad choices - for example, swearing abusivly at someone in messages. I have told him it's our rules as long as we pay the phone bill and he can make better choices when communicating with others. Explained that this behaviour ultimatly causes upset to us and we would be the ones who were shouted at by other parents. He has ADHD and is impulsive and immature. I caught him sending messages to some one on Messenger who was a dirty chat for money type service.
He is 99% positive with phone use. Calls friends to chat and play Minecraft etc but let's himself down otherwise

You are right. Tell him that you love him so much that you are willing to piss him off to protect him. You care about him and you are not alone in policing a child's phone.

Tell him that any other person he sends messages to could end up showing those messages to a teacher or senior leadership if they are another pupil or if threatening, the police.

Afterwards when it is all calm does he recognise that it is in his best interests to cut it for homework? Can he see his mistakes afterwards? If yes then great if not can you follow the possible outcomes, ie if he doesn't do his homework what are the consequences from school? Or what if that person reports your abusive message to their parent, what if they then contact the school? They need to see where their decisions can lead them.