most importantly you never say anything about how long and well pre introductions went?
I think the chasing will go down over time. BUT, If it was me, I would separate them and do more pouch swapping and cage closeness. I would make sure when they are finally ready to have a neutral or clean cage.
we have alpha gliders in colonies and they like to let other gliders know who is boss, a quick chase and a quick squabble and no one gets hurt. We don't like it but think that is part of the chain of command. At times we have taken the aggressor away for a few hours. most of the time our aggressor acts up right after mealworm feeding time, I think he is trying to make sure he gets most of the mealies.
So...
I would separate and follow introduction procedure, (again or for first time).
I would make sure to have a neutral cage. If after all those weeks you put them together again and they chase and have small spates I would let it go IF NO GLIDER is getting injured. I would also take out aggressor and while others eat maybe have him with me and give him a few treats, let him be fat and happy.
which makes me think you could add a few toys for the aggressor, running wheel, LOTS of foraging cups with treats in them (he can't guard all them.) whiffle ball with strips of fleece in them, and other stuff that might give him something to do other then guard the food.
I believe a lone glider will be fine, specially for short term, dont worry about "depression and loneliness" if you have a chance that one could get injured, injury sounds far worse.
those are some of my ideas, hopefully others will post some too.