That's true, but for Epic's tying claim they've argued that the tying product is iOS app distribution and the tied product is payment processing, which again re

That's true, but for Epic's tying claim they've argued that the tying product is iOS app distribution and the tied product is payment processing, which again relies on establishing that iOS app distribution is in fact a valid antitrust market. If that fails, they might be able to amend their claim to argue that iPhones are the tying product, but then that opens up a different set of questions about how much market power Apple has in the overall smartphone market. (They also need to establish that payment processing is actually a distinct product or service from app distribution, which is not necessarily obviously true and depends on a separate set of factors.)