- George is 100% certain that Elliot is Cheerleadra. (earlier in this storyline)
Beyond association, it's entirely possible George has no logical reason to think Ellen is "weird" at this point.
Much like Rich's problematic mental schemas weren't completely shattered, it's unlikely George's schemas about Ellen have been, either.
His exact hypothesis has been disproven, but "Ellen is suspicious" could still be a rule that exists in his mind, even if George can't logically defend it beyond "I know there's something weird about Elliot."
Which, as a concept, I find interesting.
"I think D because of C! Wait, C was just disproven. D is probably still true, though."
I'm not sure how often that sort of thing happens, but my suspicion is it's not that uncommon.