Ben, go back and read the tuff stuff. I was on board and I can assure you that the wing drop was abrupt and sudden. And at no time was the tip area stalled as indicated by the tuffs. It is only necessary for any significant area of wing on one side to stall before the other to produce an abrupt wing drop, not necessarily at the tip. As a matter of fact, in a perfectly symmetrical stall (coordinated), if the tips stall, they stall at the same time resulting in a pitch down, not a roll. Only if there is something producing an asymmetrical stall distribution will one wing drop. And the most common factor by far is yaw at the moment of stall.

By the way, in response to your previous comment, on the Cherokee, the fuselage interference may have affected the particular pattern of stall that began near the root. However even remote from any fuselage, with a rectangular wing and no twist, the stall always begins near the root and proceeds outward.

Tip stall is a fact. However it is sometimes an accurate description of what is taking place, and sometimes not.