It is a dominance thing, it may settle down a bit once he feels he has established his place as the alpha male, but at the same time, it might not. Hard to say, every glider is different.
He can also produce dominance wounds on the neutered boy, especially if the neutered male is trying to resist or get away. Be sure to check him over daily for wounds on his neck or shoulder areas. If he opens him up, you'll have to separate until he heals.
Your best bet is to get the intact boy neutered ASAP. Once he is neutered, his testosterone will lower and he will not be as aggressive. He may still engage in the dominant behaviours as he will be neutered after being fully mature, but it most likely won't be as vicious about it.
If the fighting gets worse, make sure you have a hospital cage ready to separate them if there is a dominance wound or other injury. But you won't be out of the woods until he gets the big snip.