Several sources have already indicated that Google at least recommends a device with a minimum 1GHz processor and 512MB of RAM for Android 3.0 Gingerbread, neither of which the Droid offers. So that meant that anybody buying the Droid would be buying it with some question about it running Gingerbread well, if at all. That might make it a bit of a 'lame duck' offering except to those wanting to employ root, custom ROMs and overclocking.
It has also been suggested for quite some time that the Droid 2 would be Verizon's first phone to come with Android 2.2 Froyo. Thus avoiding potentially delaying other phones from being offered with Froyo meant getting the Droid 2 out first.
So while whether the Fascinate should have been released before the Droid 2 or not is a good debate, I don't believe that delaying the Droid 2 release until October or November was a real practical option.