A more reasonable explanation could be that the piece was being carried w/o a carry license and the carrier thought he may be confronted by an LEO (shoplifting?) and the carrier ditched the piece.
Over the years, I know of situations where LEO's and licensed carriers have left a piece behind while using a public bathroom (removing the belt/holster w/ the duty weapon or concealed carry piece in the holster takes a third hand, sop is to remove the piece from the holster and proceed) and aside from the public risk it's a real failure of competence on the part of the carrier.
I once pulled into the parking lot of a municipal range before opening hours, and there was another car in the lot w/o anyone present, with a handgun and ammo sitting in plain view on the trunk lid. I waited 20 minutes or so until the range opened, still no gun owner, and removed the piece from the trunk and turned it in to the range master. Gun owner showed up about a half hour later freaking out that their gun was gone. Range master calls a cease-fire, calls me over and he and I had a heart-to-heart with the absent minded shooter. He told us he was waiting for a friend and he was worried that his friend would miss the entrance to the range so he was standing out at the entrance waiting for his friend to flag him down. Since there was nobody standing at the entrance when I drove in, his story wasn't too credible, but he didn't seem any more confused than most people.
I wanted to know why he'd leave his piece unattended, and he said he didn't remember removing the firearm from his trunk...
Everyone might have an arguable right to possess a firearm, but that doesn't mean that they're qualified to do so safely and competently.