I notice this quite often - people will be arguing completely logically but from a axiomatic starting point that I (and probably most people) would find abhorrent or misinformed.

They will obscure the axioms they're arguing from so as to not get immediately dismissed, and instead just look rational at a glance and intellectually dishonest when you ask too many questions or read too carefully.

Props to CzechTech for being upfront at least.