This might be crazy, but if you are afraid to bring it up, you could pull a Seinfeld-style maneuver and say, it's really important that we all be in the same pl

This might be crazy, but if you are afraid to bring it up, you could pull a Seinfeld-style maneuver and say, it's really important that we all be in the same place, and suggest that if the CTO doesn't want to ever move back, then maybe the whole company should move to San Diego. At least it's a way to get it out there.