Emacs or GCC alone are more impressive chunks of work than many Ph.D theses I've seen, if they were given a prettier write-up.
But besides that, it's like giving a Th.D to St. Paul - GNU & free software in general is the reason a huge chunk of software and resulting work exists at all. An honorary degree doesn't really convey the scale of the accomplishment.
So he wrote some software that more or less copied extant software, which was well used. That's undergraduate thesis level stuff. Has he done much on the theoretical (CS/Math) side to justify an advanced degree? I'd argue not
But besides that, it's like giving a Th.D to St. Paul - GNU & free software in general is the reason a huge chunk of software and resulting work exists at all. An honorary degree doesn't really convey the scale of the accomplishment.