Took 14 hours to get home from Minneapolis last week. Both times they lied about the cause, which was a mechanical, first one they blamed on ATC, second they blamed on late arriving crew.
All I'm gonna say is that in my 35 airline years, I, nor any of my people, never lied about the reason for a delay, although I have lost count of how many times were were accused of that. I am not saying it doesn't happen, just that I never saw it happen.
Root causes of delays can sometimes be very complex and multi-faceted and are reported to the DOT for their statistical data. Fudging the numbers could have bad consequences.