Idk Sluga lol, that was just my impression. From that thread it looks Mulder could be all sort of things, and Scully is mainly seen as a LSI. Their modus operandi reminds me of Delta quadra anyway. Dedication, no time for loud fun and jokes, work, missions, insights, blah blah. They don't look much like a dual pair either, Scully is very skeptical, yeah. But that's her character, because she values Te and what the official science says about ufos, and that's a kind of Delta attitude, to follow the program and adapting to it. Betas are more for imposing their own views on others instead, and neither Scully nor Mulder does that, they're guided by intuition, by external unexplainable facts, the ufos. Mulder seems the more attuned of the two, and Scully is always surprised of Mulder's actions, because they don't follow her idea of "appropriate", as they're guided by his intuitions, but she falls in love with them. She's even the one to back up all of Mulder's unbelievable claims, although she initially doesn't want to believe, because she can't. But she loves that and you can see it.. and that's Ne. Mulder is not an ENTP as some says, to me, because he's not as logical, he's more of a feeler, and an introverted one. Although for sure, he's some kind of super brainy being, but more on the visionary way that a few EII are capable of. He's no extrovert and he doesn't push his ideas, he's guided by them, because he has an inner call... but I don't wanna spoil lol.

Anyway, fictional characters are a special breed because they're just unreal and such people don't exist in real life