[abrowne]

It uses a Linux-compatible kernel interface with no Linux kernel code plus Ubuntu's userland. I guess that's why they sometimes call it Bash on Windows. I'm surprised no one's proposed "Windows Subsystem for GNU".

[azinman2]

Because the main bit is translating Linux syscalls to windows. Which isn't gnu.

[cryptarch]

Isn't the main use of WSL "first-class GNU tools for Windows"?

I can't really imagine people running anything other than development tools on WSL, and most of those come from the GNU project.