I'll pitch in, but you almost certainly already know more about this than me.
Isn't plant rot usually related to the transition from growing emersed to submersed? In that case, keeping the plants out of the tank during the cycle wouldn't do anything.
Even if bacteria were the cause for the rot, I would think you would actually have a larger bacteria colony in the tank post-cycle than during it. What do you mean by 'immature bacteria'?
I went a read just a few posts about Anubias rot, and my impression is that the cause is either from the transition from growing emersed to submersed or has something to do with how the plant was raised, handled, and shipped by the supplier. In this case, it would make no difference if the tank was cycled or not.