All people saying “boo-hoo, Apple bad, Epic good” seem to be forgetting that what Epic did wasn't just “not complying” with App Store guidelines, they did something fundamentally much worse from an ethical standpoint.
Had they submitted a version of Fortnite with their own payment platform visible, it would've been outright rejected (I'm not even going into whether that would be the right thing to do or not, but it would objectively be the obvious one); had they kept doing so, Apple might even have suspended/banned their account on the grounds of Epic behaving like a [relatively benign] troll. And in that event, with this rule change mandated by South Korean courts, Epic would be well within their right to ask for a revision of that suspension/ban, and even take Apple to court (by the way, they would likely win that case, IMHO).
Except that was not what happened, at all; Epic purposefully deceived Apple by submitting a build of Fortnite with their own payment platform HIDDEN from view, thus precluding App Store reviewers from even knowing they were breaching App Store guidelines in the first place, and only after having said build approved and available for download in the App Store did they remotely toggle that platform's visibility and accessibility to end-users.
To add insult to injury, they tried to paint themselves as the victim and Apple as the villain on the media. Any goodwill points and sympathy they might have earned otherwise (and their case would've been, I'll readily admit, very solid), they very consciously jeopardized (and indeed chucked down the drain when it comes to any Apple customer or parent with half a brain and a spine).
TL;DR: Epic behaved in borderline criminal and deceitful fashion, and Apple was and is well within their right to enact and enforce a lifetime ban on Epic. Also, on that regard, remember when we still had NVidia GPUs on Macs? Yeah, me neither.