That was 100% pilot error.
Wiki:
"Pilot error is a term used to describe the cause of a crash of an airworthy aircraft where the pilot is considered to be principally or partially responsible. Pilot error can be defined as a mistake, oversight, lapse in judgement, or failure to exercise due diligence by an aircraft operator during the performance of his/her duties."
The truck didn't pop out of no where. He should have waited for it to clear before taking off..
It sucks, but no matter what, the FAA/NTSB considers 99% of accidents "Pilot Error"