It doesn't relaunch automatically. You either have to click on the Finder icon in the Dock, or otherwise it relaunches itself if you quit all other open applications.
That's extremely funny, but I'm almost completely certain that's not as "vanilla" as you think it is. Perhaps it was enabled on the command line? It looks like
Yes you are right. I have absolutely no recollection of tweaking this, but it seems it has been done. (I just checked a different, definitely unadulterated 10.3.x install, and it doesn't have the Finder quit menu item.) Thanks for correcting me.
Screenshots:
http://www.alexmaslin.org/quit-finder.jpg
http://www.alexmaslin.org/no-finder.jpg
It doesn't relaunch automatically. You either have to click on the Finder icon in the Dock, or otherwise it relaunches itself if you quit all other open applications.