Yes, it does work...
you don't have any other tabs open when you quit.
I think this is some "new" thing Apple introduced into Safari v6 with regards to tabs and window size and the Full Screen thing for laptops and iDevices.
It should not be like this. Apple made it so that INSTEAD of simnply opening in the Home page, it opens all other tabs as well - that is ones that were open when you quit.
Yes, my Safari Prefs are set to Open to Home Page.
Even though I didn't feel this would work I did try it.
And no, trashed the caches.db file, relaunched Safari.
Resized the window how I wanted it.
STILL is automatically sizing the window how I DO NOT want it.
Apple removed the Remember Window Size from v6 that was there in previous versions.
I am getting really tired of Apple doing things like our arch enemy MS, whicvh includes tying the browser to the OS so tightly we cannot remove Safari if we wanted to (in OS 10.7 or 10.8).