I would never buy a Mac, but what's the issue with supporting Mx processors?
Are they a generic ARM platform or something highly proprietary with ISA extensions and the like?
And if Apple is pulling a Nintendo here why is this project allowed to exist in the first place? It's not like they are getting hit with an anti-trust any time soon.
The problem are really not the CPU cores itself. It's a generic arm core in terms of ISA with just a tiny bit of proprietary extensions. The problem are all the peripherals. GPU, NPU, Display, USB, Wifi, HID, sound etc etc. These all require custom drivers and reverse engineering.
Problem is, there's no such thing as a generic ARM platform. The devil is in too many details even if there was something common between some core designs.