... shows that you don't have to be an atheist to make great discoveries.

I don't think anyone is making the argument that you do. Plenty of people get through life without basic rationality, and some even do interesting and amazing things. That's not an argument for being religious though - at best, it shows that in certain cases religion doesn't completely cripple your rationality. It's still a risk, however.

As for religious people being happier than atheists, ... In my experience, the average atheist is not at the basic level talked about in this post. Slightly more rational than the average theist I've met (and I tend to more time around the smarter, more rationalizing type of theist), but still not even close to this.

Obviously that's just anecdotal, so I wouldn't bet much on it at all, but it's enough for me to question the validity of applying murky evidence about happiness and religion to a discussion about teaching basic rationality. If anything, I would say that evidence seems to more strongly indicate that we should teach basic rationality, because leaving religion without it might make it more difficult to be happy.