I just waned to add to my question. Is it possible that he will only chase the majestic back into his cave for a day or two then stop? Should I try to section the emperor off to the side for a few days? Or should I give my emperor to my lfs to babysit him for a month or so, so when I introduce the emperor back to my tank it won’t feel like it’s his tank anymore?
Sadly, your LFS gave you some bad advice. Emperators are the king of the tank. If you wanted to try adding other Angels with him, you should have put him in last. The general rule for mixing marine angels is not adding Angels from the same shape or the same oceans together. So if you want to mix, you add dwarfs with pigmys or large sized Angels. You can mix pigmys but are better off keeping them in a school of their own ( 1 male and a number of females) or pigmy's of different oceans. ( i.e. Atlantic pigmy angels with Pacific species like Fisheri or White tail. You wouldn't want to mix say an Atlantic Pigmy with either of the Flameback Angels, African or Caribbean, because they look too similar. ) Since these pigmys like coral rubble, you need to have a lot of live rock with smaller pieces scattered all around a large tank. Same with different species of dwarf angels.
Majestic angels on the whole are not very gregarious so they will hide a lot and will not usually fight with other species of Angels in their same family or defend themselves. They really should be the only large Angel specie in a very large tank. IME, the best mix with a majestic is a Regal Angel as both of these species are scaredy cats.
LOL
Just an FYI, years ago there was an article in TFH magazine about Emperators breeding in the wild. 1 male was followed and the author found that the territory the 1 male patrolled was close to a square mile and he was spawning with a female in all 4 corners. So Emperators need A LOT of space. A 180 is a drop in the bucket to them.
At this point, I would return one of the Angels and if you keep the Emp, that's it for other Angels ( especially since he's had 2 years of claiming his territory, the whole tank, so you would need to totally rearrange your decor so that all the fish would have to claim new territories if you were to try any new smaller Angel species. )
Hope this helps.