Obstructing an unnecessary investigation is a big deal only because people fear-mongered us to believe it's a big deal.
Guy should get a good slap and a 6 figure fine. Not get his life taken away.
It's a bit more serious than that. It worked out to not harm anyone or do large-scale damages (fire, destruction, etc) this time, but it was still wildly dangerous and demonstrated a complete lack and disregard for aviation safety and rules.
A more apt comparison would be throwing a table off the Empire State Building, and it just so happened to not hit anything below.