From your article: “Real-time locational marginal prices for the Electric Reliability Council of Texas remained at or near $9,000/MWh cap on Feb.” If they set the rate at 9k it would have stayed at 9k not near 9k.

What your referencing is points in the day when the price fell because rolling blackouts where intentionally created. “If customer load is being shed, scarcity is at its maximum, and the market price for the energy needed to serve that load should also be at its highest.” That’s saying if rolling blackouts are implemented then the price should be at the limit. Grid operators can’t simply turn off more people’s power to reduce the demand arbitrarily below the limit. So, prices where adjusted retroactively.

As to why that’s relevant, Grid operators are stuck with the bill. If they can maintain normal prices by simply cutting off everyone’s power to avoid losing billions that’s what their going to do. But, the are not allowed to arbitrarily cut people’s power because they dislike the current wholesale rates.

Again, choice was made about this storm, just enforcement of existing rules.