Training Issue ?
My bet is the collective was not being locked, this is the most likely explanation. Maybe this guy wasn't aware of the significance of this for an AS350. Keep in mind there are no type ratings in the US, so any Robinson pilot can hop into an AS350 and legally fly it. Not sure how much training this guy received on type. Maybe someone working in this area can comment on this.
It's easy to forget an item in a check list (especially when you are in a hurry), but you gotta know the critical ones by heart. Always lock the collective on the ground on any AS350, no matter whether you are inside or outside the helicopter !