Usurpers in AI-controlled states

[WingedIncubus]

I am not certain I understand the rule in the manual for Usurpers in AI-controlled factions :

7.5.2. Usurpers

If a Usurper faction appears in a civil war it will rejoin the original faction after 15 turns if the original state was AI controlled.

Am I to understand that whatever happens, even if it is winning the civil war, an usurper faction will be reannexed by the AI controlled faction after 15 turns?

I ask, because in my Macedonia game against Persia a number of usurper factions have appeared inside Persia. I want to support them financially with gold and troops, but if they are to simply disappear after 15 turns why bother? They will not try to secede and form their own rump states?

Thanks!

[Gray Fox]

Yes, they are eventually doomed. I had a Roman Usurper take over all of the Roman regions. So I made an alliance with them, and then they became a non-allied Rome again.

[WingedIncubus]

Yes, they are eventually doomed. I had a Roman Usurper take over all of the Roman regions. So I made an alliance with them, and then they became a non-allied Rome again.

But if it wins the civil war or has a positive warscore, surely its usurper Leader will take over, no?

[Gray Fox]

It didn't matter, because the Usurper faction vanished and became Rome.