@drq Ooof even uses the coreutils testsuite as reference.

That said it makes me wonder if uutils could have used a *GPL license, like strangely coreutils has been linking to OpenSSL since ~2013 starting with *sum utilities[1] while and OpenSSL prior to 3.x isn't GPL-compatible[2] (and so LibreSSL and BoringSSL also aren't IIRC the latter's code is used in rustls, woups).
And those kind of shenanigans is why I tend to default to a file-copyleft license like the MPL-2, because when you actually do a license review the "viral"-copyleft quite often ends up non-binary redistributable.

1: https://git.savannah.gnu.org/cgit/coreutils.git/commit/configure.ac?id=b53b0fd940382497e58a9e912f1262c2084fe534
2: https://www.gnu.org/licenses/license-list.html#OpenSSL