> Another reason we know it is that Apple has (arbitrarily) forbidden app stores that aren't open to third parties. Even if Epic wanted to make it a first-party only store (why?), they couldn't.
That's a circular argument. Apple is arguing (maybe wrongly) that Epic won't follow the rules. You can't refute that argument by saying "but the rules say they have to follow the rules".
The GP wasn't making an argument about why Epic's account was terminated.
They were making an argument about why Epic wasn't a competitor to Apple. That argument was based on the mistaken belief that Epic was looking to launch a store only for their only games.
In that context it's not a circular argument to point out that a first-party only store cannot be launched on iOS, so obviously that's not what Epic is intending to do.
That's a circular argument. Apple is arguing (maybe wrongly) that Epic won't follow the rules. You can't refute that argument by saying "but the rules say they have to follow the rules".