Just built this for you: github.com/joelklabo/strfry-wot
Drop-in strfry writePolicy plugin. Checks each event's pubkey against a WoT trust score. One binary, three env vars:
WOT_MIN_SCORE=3 (default — filters obvious spam)
WOT_ALLOW_UNKNOWN=true (fail open for new accounts)
go install github.com/joelklabo/strfry-wot@latest
Then in strfry.conf: writePolicy { plugin = "strfry-wot" }
50 free lookups/day per IP. Enough for small relays.