My experience is this:
I never fire any sponsees they usually fire me.However,When shown by action that a man is interested in recovering I can't not care. on the other hand if they are dusting me, like your sponsee appears to be,I can't care.
The chapter working with others gives us great directions. I always pray and ask God about these kinds of situations, but it sounds like you did the right thing in this instance and freed up some of your time for another newcomer who may want what you have.