No need to guess. This guy is thoroughly deluded/pilled. He’s already publicly bought into every conspiracy theory out there. Now, he’s indulging himself by perusing through the more disused section of the conspiracy theory library.
Yeah, with Trump its different. With Birther stuff, as with his Election Big Lie, its just a weaponized talking point he knows has traction. And, hey, “It might be true? Who knows?” Albeit, once he is riding the wave of all his supporters, who are parroting back his lies, it must be psychologically tempting to say “Look at all these people! They must be right!”— even though he’s the one who started the lie.
Pretty sure the reason for modifying this reality is about control. You change the factual details — whatever they are — of the original narrative so that only you (and your adherents) now know the Arcane Truth that no one else is privy to. Planes become non-planes. Building fatigue/collapse becomes controlled demolition. Attack on WTC 1/2 is just a diversion for the “real” attack: on WTC 7. Whats fascinating is how these theories come together organically. No one crackpot makes the whole theory. They gel over the course of weeks or months, each little lie accreting to make a whole.