I guess an important distinction is DAI is not 100% backed by USDC, but it is backed >50% as of this time: https://share.streamlit.io/tadzz/maker_dai_collateralization...
Tether was 100% backed by USD too, until the lawsuits.
Then it became 2,9% USD backed.
In Tether's case they are backed by almost no USD and mostly short term loans to undisclosed entities... I do not think Tether is legit, and USDC is questionable as well. Without third party auditing it's hard to trust any of this stuff.
My original response was trying to highlight how DAI is mostly made up of USDC (at this time), and USDC is a direct competitor to USDT. So in what world would it make sense for USDC to bail out USDT in the event USDT is revealed as a total fraud.