I agree with you that the "you must be this smart to ride" signs in LW comments are problematic. I'm not sure they're wrong, though. I've never taken an IQ test, but from other tests am at least 98th percentile (which is ~130). Most of the stuff I've read on LW I either agree with naturally or have thought out reasons why I disagree with it- but a lot of that comes from my reflectivity and speed of thought / reading. So LW can be a hobby for me, whereas it would be a massive time investment for someone else.

And, honestly, when I think about "what class would I love to add to the curriculum," I wouldn't start with rationality or skepticism. Critical thinking is a useful skill but it's dangerous- oftentimes, half educated is worse than not. I would start with non-violence; teaching people methodology that they can use to get along better with others. That seems like the highest impact skill you could teach people.

But I still would love to see a "rationality for the everyman" project. You seem to be talking about creating a rationality narrative- which may be problematic for the reasons you outline- but a rationality skillset should be doable.