I had a quick read of the findings, I think the decision was reasonable given the evidence provided. It seems this was an assessment flight, so the student was to be demonstrating their competence. As the aircraft veered left of center line it seems the instructor has, without verbal statement, applied right rudder. At the same time the student also applied right rudder. The aircraft very quickly swung right due to the force of two pilots providing input, and was in danger of exiting the runway, so without much hesitation the student pulled back to become airborne before going off the edge.
The judge focused on that there was possible confusion as to who was in control and un-coordinated control inputs by both pilots simultaneously. There is also a note as to why the reaction of the student is not considered contributory, basically they had not been trained in what to do if faced with a runway excursion, so that left them to do anything, including pulling back. Without guidance as what to do if faced with a runway excursion the reaction is understandable, pull back, the air seems safer than the trees. The reaction was induced by the instructors input without telling the student that they had done so, leaving the student to improvise without knowing how to. I think one point from the judge was very important, that is a lot was made about the normal take-off attitude, however spearing off the side of the runway is not a normal scenario, so prompted the reaction without thought of setting normal attitudes.
Do you even brief a student on what to do if faced with a runway excursion? Like, Close the throttle, resist trying to get airborne at an unsafe speed, etc... Sounds simple when you talk about it with no pressure or urgency, when it happens suddenly without prior thought the result could be anything. In any case we don't expect low time students to be able to handle the decision well, so when they start to lose control during take-off it's the instructors job to positively take over and fix the situation. Positive take-over is a verbal announcement and physical control, not sliding in an input here or there that could lead to confusion as to who is in control. Any training close the ground the instructor should be ready for anything.
What this accident highlights is the danger of instructors making inputs without letting the student know. Students can easily overreact and overcompensate for deviations, so the student must have realized the left deviation around the same time the instructor started to put in rudder, and put in a boot-full as well to stop it. In the past that boot-full would probably over-correct a little bit, but a few fishtails later and it would end up messy but straight. In this situation the force of the instructor moving the pedal amplified the boot-full from the student, enough to startle the student, put the aircraft towards the edge, and then elicit the reactionary response to rip it off the ground to avoid immediate danger.