Sounds like you just want to create a wall garden around your own #nostr community with a few extra steps. A illusional utopia for grown men with Peter Pan Syndrome. 

Clients are not decentralized as they can be controlled to manipulate what the users sees and experiences. The Metadata you could argue is some what decentralized with relays but even then your trusting a handful of centralized authorities to store your Metadata and not fuck with your Metadata hence the importance of a private node is important. 

Creating a bot to flag users based on opinions to decrease their likelihood of appearing in a feed is not decentralized.

That's a system of control within itself which is a contradiction to what you just said about nostr being decentralized without a centralized control.

Decentralized is a buzz word. Not everything needs to be decentralized but you can't claim your creating a decentralized app if your centralizing control with your biases. 

Not all client built equal right XI XI Ping?