> CAS is "lock free" only in the sense that it doesn't require the processor to stop the world in order to flip the mutex boolean
No, CAS is lock free in the sense that a process or thread that freezes for whatever reason while doing a CAS operation cannot cause the entire system to stop making progress (provided your hardware is working as intended).
That's the only thing that matters to say if something is 'lock free' or not, and CAS meets that definition.
If you want some other property that's fine, but that's not what anyone understands by 'lock free'.