I think this guy is trying to say that reduced supply will lead to a shortage if the price is held constant(price controls) Why? because holding the price constant will not reduce demand and the reduced supply will quickly drop to no supply and gas stations will run out of fuel. If the price is allowed to rise, the demand drops as people stop driving as much or find other ways to get around. You can see it happening in the broader fuel markets as gas gets to $4 - $5 a gallon. There is a lag effect, but oil prices are declining as demand drops and we start to look seriously at alternatives.
That’s basically it.