Yeah exactly, you want to be on Malakk/Sul at the start due to cleaves during heroism. And generally speaking, Monks are the better DPS tank, so y'know.
If your druid co-tank is having issues on the priestess, assign some interrupters. Ranged can do it so melee can stay on Sul/Malakk; there doesn't need to be a strict rotation, just 'interrupt when you can' sort of thing.