Flagellants and rout tests

Flagellants can never become the leader of the warband according to the rules. However, when the leader of the warband is OOA or stunned, you use the leadership of the highest warrior for your rout test. Are flagellants excluded? Does using the leadership for the rout test temporaily bump that model into 'acting leader' status? Or is one of the best strategies for witch hunters to get your leader OOA so you are nearly immune to routing?

In my circle we interpreted the "never becomes leader" to include "never becomes acting leader also".

Yeah, the part that's weird about the route rules and leader replacement rules is that for leader replacement only heros are eligible, but for route tests it goes by any warrior. People in my gaming group argued that they're not becoming a leader then, because otherwise only heroes leaderships would be used, never henchmen. We're thinking of making an auto-rout rule if no heroes remain, or maybe saying the best leadership that henchmen can have for rout test is 5 or 6. Haven't decided yet.