I'm not sure they could have offered a reasonable fixed rate for the available power. When the federal DOE authorized the supply of emergency power that didn't meet the usual regulations, they required the price to be at least 10x the normal price ("no lower than $1,500/MWh"). I haven't been able to find out how much of the power supply that applied to, but at least some of the power during the disaster was legally required to be sold at outrageous prices.

> ERCOT shall ensure that such Specified Resource is only allowed to exceed any such limit during a period for which ERCOT has declared an Energy Emergency Alert (EEA) Level 2 or Level 3. This incremental amount of restricted capacity would be offered at a price no lower than $1,500/MWh.

https://www.energy.gov/sites/prod/files/2021/02/f82/DOE%2020...