They do it all the time. The terms are vague and they can interpret them, or change their mind at will. This happens daily in small cases, and more so in bigger one's were Apple, out of the blue, demands a 30% cut of some adjacent business.
Apple is in this for profit - if they can adjust the rules within legality for more money - the will.
Epic probably thinks that some conditions are illegal, and therefore void. But that would also mean that Apple broke the contract with Epic when they removed the app from the store.
Apple has removed apps from the App Store and blocked apps from being published or updated MANY times.
Inform yourself.
Every single time Apple removed an App from the App Store is because the new version was somehow in breach of the T&Cs.
You could say that the rules was applied unfairly to Hey but nonetheless the T&Cs were clear as day about off platform signup/payments because it protects consumer from sham companies.
When Catalina was released, they kicked out Luna and Duet after having copied their features in Sidecar.
When they released Screen Time, they kicked out similar apps from the App Store, despite being here for years.
The list is endless.
And they would get quite a few allies then. See an earlier proclamation and fight by Spotify: https://timetoplayfair.com/timeline/
What a ridiculous thing to say.
1) You make it seem like Apple are some capricious God like entity that any moment will completely change the underlying terms and conditions you agreed to when running your business in iOS. Its simply not true. If you remove this one situation with Epic its literally never happened.
2) Consumer trust in Apple flows onto any company that is on the iOS platform. You expect Apple to give this away for free? It provides immeasurable benefit to most businesses insofar that a consumer is far more likely to purchase goods or services knowing that Apple have 'vetted' you simply by being on the iOS platform. By Apple being so strict and stringent on App Store requirements you know as a consumer they aren't doing things in the interest of the vendors which in turn benefits legitimate vendors.
3) Epic flagrantly violated the terms they had previously agreed to simply because they don't agree to the 30% cut. That style of negotiation is absolutely atrocious and Epic should be the ones being punished not Apple. If they felt so strongly about Apple's anti-trust liabilities they could have formed an alliance with other businesses and lobbied governments globally without breaking existing T&Cs. They probably would have won too and been able to get the cut Apple take to the same level that it costs Apple to run (say 15%). Instead they are trying to bully Apple into doing something that benefits Epic and Epic alone.
Epic are 100% in the wrong here.
Note I am neither an Epic nor Apple user.