Normally you use sorbate and campden to completely clear cider a few days before sweetening. By adding it at the same time as the sweetener, I"m not sure the sorbate will completely inhibit fermentation from restarting. If the cider was completely and totally clear, then maybe. But if the cider wasn't clear to begin with, the sorbate won't "work".
In any case, aging does great things for cider and cold conditioning really helps drop out any excess yeast and acids so that helps a lot too.
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