I also (perhaps unfairly) assumed my audience would follow along easily enough in my slight equivocation between "ethical" and "rational."

Not unfair, just more wrong. This is human bias. We identify with the in group identity and associate all morality and even epistemic beliefs with it. It doesn't matter whether it is godly, spiritual, professional, scientific, spiritual, enlightened, democratic or economic. We'll take the concept and associate it with whatever we happen to think is good of or be approved of by our peers. People will call things 'godly' even when they violate explicit instructions in their 'Word of God'. Because 'godly' really means 'what the tribe morality says right now'. People make the same error in thought when they use 'rational' to mean 'be nice' or even 'believe what I say'. This is ironic enough to be amusing if not for the prevalence of the error.