Apple owns the CUPS source code. They can already do whatever they want and are not bound by the GPL. In fact, the current GPL licensed CUPS already comes with

Apple owns the CUPS source code. They can already do whatever they want and are not bound by the GPL. In fact, the current GPL licensed CUPS already comes with an exception clause to make sure macOS printer drivers don’t have to be released under the GPL even if they link against CUPS: https://sources.debian.net/src/cups/2.2.1-8/debian/copyright/#L50 https://sources.debian.net/src/cups/2.2.1-8/debian/copyright...