It would be a signal.

In the long run, it would affect what sort of contributors and users GNOME would have -- people from the Open Source camp who think proprietary software is a nuisance but not "immoral" or "evil" as Mr. Stallman suggests. Or people from the Free Software camp who think all proprietary software is "immoral" and "evil" and should thus be forbidden by law.

Of course, it would also be a blow for the Free Software community if a major project decides to stop supporting/promoting its political goals.

In the short run, of course, only a few words on the GNOME homepage would have to be changed.