I'm hearing he is mostly piggy backing on others work, as from what I'm told he was a quantum skeptic and joined the game late (honestly just repeating informal chats with some people interested in that topic)
I'm not sure how that could be the case. Dan was among the first to push the notion of post-quantum cryptography, along with Johannes Buchmann and his research group at Darmstadt (which credit him in [1] with the coining of the notion of "post-quantum cryptography"). Both organized the first PQCrypto conference in 2006, and edited the first book on post-quantum crypto.
