There is literally no reason to not allow cross-compiling. From one language into Objective-C. From one library into Cocoa. The ONLY reason to prohibit that, is to try to force people to stay inside your walled garden, with no way to climb out, allowing you to simultaneously develop apps for multiple (non-iOS) devices.

It was a dick move, and thank goodness they got called out for it.

And yes, it was to try to enforce a monopoly.