Green tiger barb with no tail

I posted about a week ago concerning my green tiger barb with the tail injury. My local aquarium shop has confirmed that his tank mates nibbled his tail off. I have him in the tank in a nursery “box”. How long until his tail grows back? Will the other barbs ever accept him? He seems listless. I’ve tried giving him a break from the little netted box a few times under very close observation and one of the barbs immediately started following him and nips at his tail. Should I return him to the store for re-homing? (they will do that)