Eehhh, I've been skeptical of Bitcoin in the past because of its volatility, but this is very unusual. It's been rather stable on a week-to-week basis for a long time.
Yes, there were in fact $4/gallon, $5/gallon, and even $8/gallon gasoline and diesel prices posted, many by noon. This also increased the price of everything shipped by truck for a while, too.
Prices came off that peak quickly, but took months to years to revert completely.
The price of a christmas tree drops precipitously the ~9PM on christmas eve every year, that says nothing about the value of a dollar.
Not saying that's what did or didn't happen on 9/11, though.
[1] - https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=E...
If I charge $1000 to eat a cracker from my cupboard, the value of a dollar didn't suddenly decrease by 99.99%.