No you don't have to rob them for them to survive. According to the books I've read they will eat any excess honey they don't need before winter sets in. And if you just want them for pollinating you will only need two supers for them because that's all they need to get through winter here in KY. They will swarm more that way but that just increases the local honey bee population in your area.
My brother got a hive from us for that purpose but he's so protective of his bees he had us put a third super on his hive a few weeks ago. We added a queen excluder while we were at it in case he changes his mind about robbing them of the third super. He wanted to make sure they had plenty of room to store honey so they wouldn't leave him.
