Think Apple's argument about Epic having previously flouted the rules openly might be good enough. For a third party app store, Apple is pretty much giving the keys to your phone to the said app store. If there is a company which has demonstrated they won't play by the rules, it's not a huge stretch to say that it may harm the security of the model. While the EU wants the company/iphone to be more open, it also puts the onus of keeping it secure on the company itself.<p>Another reason I believe they are on sure footing is that they got the rejection from the law firm, which I presume knows what they are doing, just as they did during the 2020 shenanigans from Epic.