Earlier quoted context omitted.
I expect they don't actually care whether or not people run Linux on macs. I mean they used to let you run Windows! Probably the real reason is just that it's extra work - both in terms of producing the docs, and in dealing with complaints when they change things. From their point of view it's extra work with no benefit to them.
Yep, I suspect the goal is to reduce support footprint/burden to the absolute minimum possible, which is also why they don't maintain their legacy virtualization/translation layers indefinitely (Classic mode, Rosetta 1 (PPC → x86), Rosetta 2 (x86 → ARM)). The benefit is being able to make major changes, refactors, etc with relatively little delay and encumbrance. This applies on both the software and hardware layers.…
Apple is not interested in tying their hardware design to Linus Torvalds.