Moderation should be done by clients, not relays.
"Decentralized Moderation" would be client software giving you the power to select which filtering rules you would like to apply, and which ones you would like to ignore - you perfectly know how the decisions are made.
These filters could be purely algorithmic (number of likes from people you follow, friends in common, trigger words, you name it), or human-curation like you suggest. You could then mix and match what fit best for you, but you always stay in control.