The second dispute assumes that every specific practical rule of an earlier dispensation must necessarily remain unchanged for all subsequent communities. On that assumption, any later modification of practice becomes an objection to revelation itself.
The key distinction is between enduring religious principles and particular legal arrangements suited to their addressees and circumstances. Belief in God, moral accountability and truthfulness may remain constant while some details of religious law differ.
An earlier command can have been genuinely authoritative for its original community and time without requiring that every future community receive precisely the same rule.