And I was able to get Matthew Zipkin back on the show to discuss.

Main summary (Mike’s interpretation): a 51% attack needs to be done w/ equipment that is different from the standard bitcoin SHA256 gear. So that person would need to get enough of this special equipment to take 51%. The 51% would only be for the blocks that it is able to maintain that control. It cannot access the wallets / private keys - so it could not modify DNS records of the names on the network. Biggest risk identified could be 51% of a valuable auction for the 5 days the auction is on to win that auction w/o others bidding. To go back in time enough to modify older auctions would be very , very, expensive / close to impossible.

Here are the links Matt mentioned during the talk:
https://bitcoin.org/bitcoin.pdf
https://bitcoin.stackexchange.com/questions/658/what-can-an-attacker-with-51-of-hash-power-do
https://bitcoin.stackexchange.com/questions/95553/why-is-a-51-attack-guaranteed-to-outpace-the-rest-of-the-networks-miners-does
https://bitcoin.stackexchange.com/questions/101557/how-to-secure-a-blockchain-based-on-pow-against-51-attack
https://www.crypto51.app/
https://www.nicehash.com/my/marketplace/HANDSHAKE
https://www.goldshell.com/product/goldshell-hs5-20220112/
https://miningpoolstats.stream/handshake
https://news.bitcoin.com/bitcoin-gold-51-attacked-network-loses-70000-in-double-spends/
https://www.coindesk.com/markets/2020/08/29/ethereum-classic-hit-by-third-51-attack-in-a-month/