The paper is older than Mainline itself, if it was worth the paper it was printed on, we would have had such DHT by now, Nostr didn't invent WoT... people had many trust networks a decade ago... amounted to nothing, and I bet this will never change.
Discussion
I wouldn't dismiss the possibility of a wot based DHT simply because it doesn't exist. Perhaps it has been researched already but had some other issue, it's unclear.