More significantly, you seem to have missed his point: he isn't saying that fees are hundreds of dollars, but that a 50 dollar fee is too expensive for any transaction that isn't at least hundreds of dollars.
That's not representative of the market rate, so is irrelevant to the discussion of whether fees are cost prohibitive.
For example at the same moment in time as the guy who accidentally paid a $500,000 fee (in the same block), you can see a bunch of transactions that went through with $2 and $3 fees. Yes that's still high in a relative sense, but it's not tens of thousands of dollars.
To determine whether corn is cost-prohibitive, you need to go by the market rate, not link to a top-10 list of the most overpriced corn purchases ever made.
One person unilaterally paying far above the market-clearing rate didn’t significantly change what others needed to pay.