They knew more than 60 days prior that there was a cash flow problem and that the current path was unsustainable. What they didn't know 60 days out was how long they were going to make it. Too many "undetermined" in that equation. The tombstone just expedited the process.
Without that tombstone you may have just received a 60 day WARN Act notice, but I'm not confident it made that much difference. Maybe it went from 8 weeks out to 3 weeks out...
A forensic accounting could tell you what the forecast looked like at current business trends, with pre-tombstone and post-tombstone freight volumes.