Yeah. Sometimes you gotta take the punt. And “too professional for us” is probably not a bad punt.
Not everyone will approach the same ethical situation exactly the same way, and that doesn’t turn the difference into a (proverbial) Federal case.
I try to believe in more grace in a situation of one, but again he wasn’t the only competitor either and maybe the more-ready chap would win out after all. If wise, the formal guy might take a hint and see if less formal would suit his next interview better. I’ve learned a lot about business in the school of hard knocks. Co-workers can be jerks, so can bosses be. Might be best to go on by.