If the support system is only available for your own cities or conquest, you still have problems.
1) Players with a single city still cannot dodge. Players with more cities but none on the same island cannot dodge without ships/transports.
2) Cannot tripwire other cities, to check for conquests or to see who is farming them.
3) Cannot spike farm cities, to destroy enemy farm raids.
4) Can abuse the system by launching a Colony Ship, then launching support, then recalling the Colony Ship. Thus, sending support to someone.
If you reduce the BP for victory processions, you increase to overall free city slots and make it easier for people to conquer, but in no way does that discourage people from working together. If anything, it encourages it more because people are forced to fight more often and thus have to find friends to help them when they fight.
You are right, condor the destroyer, that the point is to develop ideas. Instead of developing current ideas to come up with solutions, however, you are suggesting more ideas that in turn produce more problems.