They're still trying to sell the RAZR/MAXX, while the Bionic has turned into a freebie phone that doesn't get any advertising or push from Verizon (actually, I don't even see it on the Verizon Wireless website anymore). From a business standpoint, you'd want the phones you're really trying to sell to get the new update first before the ones you're not pushing (or not even selling anymore).
Of course, people who bought the Bionic will see it much differently. But based purely off business, it makes sense to update the RAZR first. Why give someone the option of a free phone with essentially the same features as a phone that will cost a couple hundred dollars up front plus the two-year contract?