I would agree, I did not know the details of the plane coming or going, what it was or wasn’t carrying, but in a plane of that age, mechanical failure could absolutely be an issue.
In a cargo plane, I always think load shift first, pilot error second, and mechanical third.
But no load rules out load shift.
There were 9 onboard so about 5 were pax. Probably just catching a hop to Davis Monthan.