This is still centralized. You have 1 place that stores the trust ratings. The fact that it crowd sources the ratings doesn't change that it's centralized.
It also doesn't really work. You have to choose between not gettimg messages from those outside your circle of trust or getting spammed.
Thank you for this fascinating write-up. It's given me a lot to think about. I'm quite curious as to why no existing social networks have tried to implement your ideas in a meaningful way, and to a lesser extent why no new start-ups have.
Perhaps when I have a few hundred million to invest in a better platform I'll reach out! (One can dream).