Isn't what the author describes simply a mental model to amplify an egocentric worldview?
Most people are about average and those 'alright, not weird' decisions are on average the best decision not just for the individual but also for society. That's why they're not weird.
"Average" people are not literally an average of all the people, they are individuals. The decisions the author is talking about are personal decisions, and at some level you have to believe that being yourself is going to benefit the world more than trying to be some bland character who makes all decisions in reference to society. For example, maybe you start a business for a niche market you happen to be in.
It's more like a way to counteract lots of social conditioning.
Most people are about average and those 'alright, not weird' decisions are on average the best decision not just for the individual but also for society. That's why they're not weird.