Dismally inexperienced and unsupervised Grade 3. The Grade 1 who taught this instructor, and the Grade 1 who supervises this instructor, should also be under the microscope.
The grades noted are not what I recognise but are comprehensible. Where the prospective instructor is required to compete a formal course of training it must be unlikely that the FIC instructor would have been tolerant of such sloppiness. This instructor will have been bored and without care allowing his concentration to wander elsewhere. Not even bothering to secure himself and maintain both his feet and his hands at the controls demonstrates his arrogance. The outcome was always foreseeable by any instructor except by a fool.
..... the loads will increase relatively slowly, giving the student adequate time and opportunity to quantify the changes .....
Absolutely, all teaching, to be of any benefit to the student, must first be briefed, even when airborne if that's the way it is, so that the student is always part of it all. There cannot be anything gained by having the student continue flying subject to these loads because that is not the point. Whatever the chosen out of trim experience what is most important are the actions the student learns to take to correct the issue: i.e. maintaining the desired attitude whilst correctly retrimming to balance out the loads. From this exercise the student will have learnt how powerful out of trim loads can be either from a misseting, a jammed trim and the not infrequent runaway of electric trims. How to resolve these last two, being malfunctions, should be dealt with within a separate lesson.