Re: It's not what you say but the way that you say it
as Apple is the benefactor of the subsidy, it's up to Apple to challenge it.
I do not believe that is correct. The EU are not telling Apple to do anything, they are only telling Ireland that they have done something wrong and must correct that wrong. It is for Ireland to argue the case they did no wrong.
I do not know what the mechanism would be but I expect there is some channel for Ireland to argue that (1) the determination that Ireland gave 'illegal state aid' to Apple is wrong, and (2) the amount Ireland is being asked to recover from Apple is wrong.