And yet, ancient Windows binaries will still (mostly) run and macOS allows you to compile for older system version compatibility level to some extent (something glibc alone desperately needs!). This is definitely a solvable problem.
Linus keeps saying “you never break userspace” wrt the kernel, but userspace breaks userspace all the time and all people say is that there’s no other way.
sudo is MIT also (or something that looks like MIT at least). https://www.sudo.ws/about/license/
The more critical part wrt license is real coreutils which they also want to replace.