Maybe, but this isn't discussing using an app on your phone. This is discussing an app using a service that is not on your phone. If you're running a model locally then sure, they probably can't do anything about that. If it's a product being sold by a company then they can.

As an obvious example, they can ban you from using a child pornography app (regardless of if it's local-only). I'm certain you agree that they're allowed to do that, right? It's obvious in that example. What's the difference with AI if they ban that?