So, for giggles I decided to add Batman to my friends list. Turns out, someone actually has that name, though I could've sworn we weren't able to do such a thing.
... this is kinda hard to explain but in some ways, NPCs are the same as PCs. The iconic NPCs that we see repeatedly... the game treats them the same as PCs. Lemme explain it through example. When "Fight for the Light" launched, a couple guys in my league were asked to change their character names. They had named a couple alts after more obscure real GL Corps lanterns. The devs needed the names back to be able to add those NPCs.
This person does exist on usps. I believe it's just some kid though. If by chance I do find him/her in the watchtower, I inspect them and usually see them wearing like t2 pve gear lol. To have such iconic name, I was expecting maxed out gear the first time I inspected him.