I'm sympathetic to marcan's points and I don't think Apple is likely to do anything like this, personally, but this argument isn't very convincing. All this means is that they can't release a firmware update blocking use of a third party OS on existing hardware (contra techrat).

OK, great, but we're talking about a manufacturer that makes products designed to go in the rubbish bin 2-4 years after manufacture (witness the half dozen comments by users in this thread saying they have already put their M1 computers in a drawer somewhere!). Apple are constantly iterating, and the goal of a project like Asahi is to stay ahead of the game and continue running on new hardware.

The proper and correct point that techrat should have made is that the second something like Asahi is a threat to Apple for any reason, Apple can release new hardware that's locked down similar to iOS. You'll even have people on this site defending the changes too, in the name of security or something.