Dunno, maybe you're right. I agree the technology choice is very bizarre, but have you noticed the emphasis on Unity in the last two WWDCs? It's clearly the game engine currently "blessed" by Apple.

I think there's a confluence of factors driving this. Foremost, they need a way for developers to make games, especially in the AR/VR space. SpriteKit and SceneKit have floundered, and RealityKit is not a complete solution to make games, let alone cross-platform games. They can't show any favor to Unreal Engine, even though it's superior, because of their fight with Epic. I wish they would invest more in something like Godot, but Unity has more marketshare (for now).

C# is a great language, and Apple is pragmatic enough to realize the cross-platform potential is much greater than Swift's. From what I've seen, Swift has little traction as a cross-platform tool compared to Mono. Lattner's departure took some wind out of the Swift sails, too.