Fortnite Apple row: Microsoft backs Epic in court filing

Microsoft said denying Epic access to Apple's developer tools would prevent Epic from supporting Unreal Engine on iOS and macOS, and will place Unreal Engine and those game creators that have built, are building, and may build games on it at a substantial disadvantage".

Apple's discontinuation of Epic's ability to develop and support Unreal Engine for iOS or macOS will harm game creators and gamers," it added.

Microsoft uses the Unreal engine for iOS and macOS games, so it shouldn't come as a surprise that Microsoft would back Epic. At least - it shouldn't come as a surprise if you know how the gaming industry works, which Apple people obviously do not.