Given the price volatility of crypto, that sounds absolutely insane to me. Also, I don't think this prevents a run, on the contrary, when everyone hits the sell button and cannot actually exit then panic will ensue.
True but it still makes a single day hit via Coinbase users predictable - which gives them data they'd need to pull different levers including when they use reserve funds they're controlling for buy orders from large institutions; likewise they'll know when the bank run is trending too fast and they'd need to hit the breaks by making Coinbase inaccessible.
The exchanges handle that part of the "problem" by simply having an outage. The withdrawal limit solves the rest of the problem by limiting how much USDT can be converted to USD.
