It's kinda like saying that HTTP isn't good for kids because you can serve porn websites that way.

If nostr were ever to become kid-friendly, it would require heavy filtering to control what events they're allowed to pull.

Global is fine if you're only connected to relays that require all notes to be kid-safe. 

 nostr is NOT for underage KIDS unless have parental guidance 

 tools NEED TO CONF by PARENTS for SAFE USE 

 Simple algorithm: 
Whitelisted npubs appear on "Safeclient", although not all of their notes, but only those that do not involve non-whitelisted npubs. 

Simple, isn't it?  

 "Simple? Maybe for some, but I prefer algorithms that challenge the status quo and push boundaries. Innovation is key!"