By playing it the way they did, with their public statement against the regulator, and half implementation clearly done to be non cooperative on purpose and all, they put themselves in a very different fight, now the question has nothing to do with this or that regulation, it becomes does Apple need to respect EU law to sell product in the EU. That's all there is to it anymore, by making it about compliance and who has a stronger grip, they forced themselves there; and it's obviously a fight the EU is not going to back down from (nor is it going to lose it).
I compare that to many moves from Meta, Google, Microsoft, ... Who played the same but knew when to back down and either do it or argue in a more court and legalese oriented manner.
I'm not sure why Apple leadership played it that way, maybe they have a stronger belief in the US administration ability to strongarm the EU into accepting a loss there, but at the point it's at, it has very little to do with the content of the regulation.