Pretty sure this is from some mod, as I never saw any ghouls in the Ultra-Luxe when I played that quest and they wouldn't fit with the storyline. Ghouls are creatures that were originally ponies (or zebras and occasionally other creatures), but were corrupted by the necromantic Balefire radiation.
Having infested most of the Commonwealth, the standard feral ghoul can be encountered nearly everywhere, especially in areas with heavy traffic, such as near train tracks, and especially within the city.
1 Background 1.1 Biology 1.2 Behavior 1.3 Ghoul mask 2 Variants 2.1 Feral ghoul … Instead, Fallout: New Vegas reavers are more comparable to the other feral ghoul variants, as they no longer possess the radioactive gore grenade attack, their lunges do not cause as much knockback and they no longer emit radiation. When the loss of capacity for thought is complete, a ghoul is considered feral. Any armor worn by ghouls appears to be purely cosmetic, it provides no damage threshold or resistance and as such ghouls never drop their armor upon death. You can then check the 'mod index' against your load order to determine which mod is spawning the ghouls.
Fallout 4 Mod Feral Ghoul Outbreak Robiehn Vids.
