I was concerned about this aspect initially, but ZoL has been going for many years now. At this point even Debian (the most purist in terms of GPL consideration

I was concerned about this aspect initially, but ZoL has been going for many years now. At this point even Debian (the most purist in terms of GPL considerations) includes ZoL in it's official repository. It doesn't distribute binaries, apt just builds the kernel module automatically. Frankly, if even Debian can use it, it's a non-issue.