Thats precisely his point. Contagion causes the break. Analogous to a bank run or the ruinous fall of the Thai baht in 97/98. Nobody has any real info on whether the bank has enough reserves, nor do they care. They just dont want to hold the asset.
In this case, they do. DAI's system is run entirely on the blockchain. It's auditable and decentralized. The biggest risk to DAI is if the value of the collateral crashed below the amount of DAI in circulation. The system has incentives in place to prevent this from happening. I'm not saying it's bullet proof, but I think it's a highly resilient system. I think adding multiple types of collateral should protect against the situation where ETH drops rapidly to near zero.
