This about hypocrites if they apostate and hence, possibly would go fight the Muslims. As they already turned away inwardly (they hypocrites), this about them leaving the religion. It's only because of this possibility of faking peace and fighting Muslims, they weren't allowed to hang around (because they polytheists were at war with Muslims). It said, however, if they are returning to a people with an alliance, then let them go. As for those returning to people who fight you, only in the case, they don't offer peace and withholding their hands and withdrawing from you, can you kill them. It didn't allow it if they offered peace, withdraw, and don't fight. It's clear.