I had the same thought. This very much feels like a derived work. Since they (aim to) replicate the behaviour if the gnutils, and not just some generic posix ut

I had the same thought. This very much feels like a derived work. Since they (aim to) replicate the behaviour if the gnutils, and not just some generic posix utiles then I think it would be hard to argue the GPL doesn't apply in a legal sense. I think in a moral sense it very much is a violation, since the GNU authors presumably intended for their work to be built on only by further copyleft works.