No, they are claiming that history did it right: Obviously leaded gasoline actually did appear to be the better choice at that time, or else people would have just used the non-patent-encumbered ethanol.
The grandparent is the one claiming history did it wrong, by using leaded gasoline even though ethanol gasoline would have been the better choice.
"Obviously leaded gasoline actually did appear to be the better choice at that time, or else people would have just used the non-patent-encumbered ethanol."
Eh. "It could only be this way, because it was" is a textbook definition of begging the question and circular reasoning. It's entirely possible that there were multiple extrinsic reasons that lead to this situation that aren't "leaded fuel was just the better option". Marketing/PR, industry momentum, regulatory capture, cost-of-entry into the fuel industry. In fact it was noted below that the leaded fuel inventor has partnered with GM.
This is exactly what the GP meant by invoking History vs. Econ 101. You're assuming that this simplistic model of price/demand is an inevitable law of nature even though there are countless counter examples throughout history of the wrong decisions made for the wrong reasons.
This is with the caveat that the inventors had a close association with GM, who presumably could have altered the design of the engines to be compatible with ethanol gas if they chose to. The profit from the patented additive was incentive for them to not make those changes, presumably helping to ensure the other fuel producers couldn't use a different additive.
The grandparent is the one claiming history did it wrong, by using leaded gasoline even though ethanol gasoline would have been the better choice.