It does not matter since nothing can happen to you if you don’t pay the fine.
AFAIK the IRS simply adds it to your tax bill and then if you don't pay it, exacts the same retribution as if you don't pay your taxes.
That's the whole point of using the IRS. It can destroy anyone's life on a whim. And it will. Bet on it. This is going to be intimidation of the first degree.