Tip stall might be regulated in full-scale aviation, but it exists known as 'aileron reversal"... and is mentioned as a genuine problem..
One site which looks at stall characteristics:
http://flighttest.navair.navy.mil/un.../FTM108/c3.pdf
For model airplanes, tip stall IS a major problem, it occurs in many different types of planes, and from what I've observed, and flown, its cause is as I described, a wing close to stall with an aileron deflected down, rolls to the down-aileron side. It doesn't yaw, it rolls.
I've seen one full-scale tip stall, and been in Tristars which demonstrated the "nose-slice" at stall..