Something to keep in mind for Sollux is that he had a tendency to experience rather rapid and intense mood swings early on, which can definitely read as a sort of airheadedness. But it's more that he's stressed as fuck constantly and doesn't know how to deal so he goes very quickly from "fuck fuck fuck thii2 i2 horriible 2hiit" to "fuckiing whatever ii dont even care about thii2 2hiit" to try and cope, and then goes back to more intensely emotional states because keeping those down ain't easy, resulting in the flippy-floppy vibes. That's at least my read of his character in early hivebent at least.