From what I understand about the Fleet Leader system. A Fleet Leader can set another Fleet Leader to be Demoted from its rank. After some time passes, then that Fleet Leader drops in rank. Another Fleet Leader can save the Demoted Fleet Leader so that they retain their old rank. All the details are here.
Not entirely sure about how it works with alts. Is every alt of an account demoted at the same time in case of compromised accounts or can a player with a compromised account save his alt from demotion?