One does not need to follow a religion for decades or earn a doctorate to evaluate claims made by one of its adherents.
That's EXACTLY what you need to do actually.
By that logic, the only way to agree or disagree with Heaven's Gate would be to follow them for two decades. By that logic, only Ph.D's are correct about anything, and only in their specific field (hint: Peterson has a psych degree, not a religion degree).
I'm familiar with Christian ethics. I was raised in a religious household. I practiced Buddhism for four years. I've been to church over 500 times. My priest recommended me a book when I was 14 called Nihilism: The Root of the Revolution of the Modern Age in which an Orthodox priest lays out his case for a world centered around Biblical truth. It's very similar to Peterson's spiel, although more intense given it was written in the early-1960's. Peterson tones it down a lot more for modern culture but the central outlook is the same. It's anti-liberalism, pro-hierarchy, pro-God, anti-casual sex. It really has everything.
Much more important than being "nuanced and educated" is being correct. Arguments from authority have no place in rational discourse. Peterson could be piss-drunk and screaming his truth and it would be just as valid. History is full of nuanced and educated views that turned out to be wrong, disagreeable, or worse.
The only thing I find novel about Peterson is he's managed to convince young people to love something they normally hate. That takes skill.