Not necessarily. The non-GPL utilities the GNU coreutils are based on are presumably licensed as MIT, ISC, Public Domain, or similar. If that is the case, those licensing regimes don't forbid adding extra restrictions, so adding the restrictions of GPL would be permitted, and the new derived (again, assuming interfaces are copyrightable) work would operate as being essentially GPL licensed. Things get murky as there are proprietary utilities too that coreutils are probably based on, but then there are also specifications of behavior (SUS, Posix) which might or might not sever the "derivation path" of the work, or might introduce further licensing constraints.