Earlier quoted context omitted.
"The interesting bit here is that is actually quite hard to figure out why what they did was illegal" I wouldn't go that far. Each RIN needs to correspond to some physical bio-fuel. They were generating RINS but not manufacturing the corresponding fuel. Seems like straight forward fraud. Now had they been actually making the fuel but then dumping it in the trash and just selling the RIN I agree it would be harder to…
You can't exactly affix a number to a specific gallon of bio-fuel. That's where the whole scheme goes off the rails, to create unique ids that only exist in spreadsheets with no 1-1 link to some quantity of product. It's a liquid, not a box of stuff.
Nothing was made, nothing was sold, but he fraudulently tracked a creation and sale by creating the RIN.