but between the missing memories and the hybridization Quirrellmort doesn't consider them to be worth the trouble. Keep in mind that there is a nice theory about not being able to lie in parseltongue.

I'm not convinced of the theory. Very tenuous and circumstantial, and not part of canon, AFAIK.

I expect anything Quirrell says to be a mix of half truths.

Missdirection to hide true ssecret.

That much seems true.