Great! So instead of "he refuses to make eye contact" being a sign of lying, it could
also be a sign of spectrum disorder. Now it's not a binary lie detector; it's additional information.
FWIW, though, this is one point where I break with
@iserith. (And I suspect it's not a major part of their DMing, anyway.)
Instead of (abbreviating here):
"Do I see any signs of lying?"
"Roll"
"23"
"He's fidgeting."
"Ha! He's lying."
I would prefer:
"Do I see any signs of lying?"
"What are you looking for?"
"I dunno...fidgeting, refusal to make eye contact."
"Roll"
"23"
"Yeah, he's fidgeting and refusing to make eye contact."
"Ha, he's lying!"
(DM, thinking, "Actually, he's autistic and has a bad poison ivy rash.")