They should have to pay it eventually.

BK only erases debt incurred PRIOR to the BK date, anything incurred after the BK filing must be paid. And BK cannot eliminate everything...taxes and most criminal fines would have to be paid as well as some civil judgements. I'm not sure where FAA fines fall in the spectrum but if I had to guess I suspect they can't be washed away.

Otherwise nobody would do ANY business with an entity in BK proceedings...every pilot would have to pay cash for fuel at every outstation.