This isn't a port - it's a re-implementation without any use of the original source.
That's also not all that's happening. It's also making improvements like better internalization support, better error messages, and a small handful of other extensions.
I have had to tell them repeatedly to stop copying tests verbatim, including the original comments from GNU coreutils. So I doubt this is true, which is frustrating.
If they followed the license nothing. My uninformed knowledge is that the rust based rewrite is MIT, the originals are GPL, and you can't include GPL code in a MIT licensed project without making it GPL.
Ehh... Technically yes but when you don't own the copyright on the tests you need to be very careful against creating derivative works, and you need to preserve both licenses in the distributed source.