> I'm a little confused as to why projects like this support macOS since at a minimum it's a TOS violation.

As others have pointed out, emulating macOS is only a ToS violation if done on non-Apple hardware, and this tool supports macOS. There is a legitimate usecase of running macOS VM on macOS.

Sure, you could use some apple-provided emulation tool instead of QEMU but that's a matter of choice, not a violation of ToS.

Disclaimer: I'm not a lawyer. This is not legal advice.