I see that as more of an award that only the current host would have. This would be done to prevent confusion on who is the current host for a contest and who has been a host.
While the contest is underway the host would have the "Robo Host" award. Once the contest is over he would default to the "Robo" award and the next host would receive the host award. This makes it easier for players to know exactly who to talk to.
Now there could also just be two awards, one for previous hosts and one for current hosts, or there could be a member group similar to Miner of the Month. The current host would be given the Host group while all others would have the award.
Or just give the host award to any and all hosts and let you guys deal with the confusion and be done with it.