The guy in the van who stopped to help was taking his daughters to their tutor. He had no idea what was going on.
Edit: Oops, apparently it was his daughter and his son, not 2 daughters.
It doesn't even matter if he had an RPG. Killing everyone in the area because you see someone with a weapon is not the proper course of action:
At 4:08 to 4:18 another misidentification is made by Crazyhorse 18, where what appears to clearly be a man with a telephoto lens (edit to add: one of the Canon EF 70-200mm offerings) on an SLR is identified as wielding an RPG. The actual case is not threatening at all, though the misidentified case presents a major perceived threat to the aircraft and any coalition forces in the direction of its orientation. This moment is when the decision to engage is made, in error.