It would be possible to give Faction Leaders FR5 powers. Somehow. (Edit: I stand corrected.)
However, it's not something the Admins want to do, because it really does open up a whole new can of worms. Mainly because of accusation of bias and malicious FR5'ing.
Edit: Which is something I would sincerely hope would not happen, given the significant responsibility placed in the hands of faction leaders. I trust they'd respect the privelege.