Yeah, I see the pun. But leaving the GPL license is a very bad idea in my opinion. If we have to rest son shoulder of giant, I'd prefer them being made of concrete, not dust. Coreutils are really a common and should be protected against appropriation.
Depending on how much a rewrite it is, GNU's intellectual property may be enforced at some point. But that's a tricky question for a lawyer. If it were me, I'd have asked GNU first.
Um, GNU coreutils is a reimplementation of various AT&T UNIX utilities. It's irresponsible to say GNU has IP rights to this implementation, especially where GNU has done a similar reimplementation(!), and where EFF, etc., has made contrary arguments, as amici, in cases like Oracle v. Google.
Nobody is going to steal a coreutils implementation, make a bunch of internal contributions to it, and yield a competitive advantage through that. The whole point of coreutils is that it’s old and stable and coreish.
In the real world, corporate engineering middle managers do not understand the GPL and do not understand how it does and doesn’t restrict them. They avoid it rather than taking the time to learn it.
Depending on how much a rewrite it is, GNU's intellectual property may be enforced at some point. But that's a tricky question for a lawyer. If it were me, I'd have asked GNU first.