Gatekeeper/notarization are intended to stop malware, which Unreal Engine is not. Apple may well have a valid business dispute (over another application on another platform), but it's an abuse of the system and control they have to obstruct a Mac owner from running non-malware software on their own computer.
Luckily the court stopped them retaliating in this case, but it gives me reason to be concerned about expansion of the "it's Apple's device and will always act in Apple's interests over the owner's" mentality from iOS towards Mac desktops.
