I have a bit of time in G-SDTL myself and sad to see that happen to it. When I did the G2 type rating some years ago, it was drilled into me about the left pedal and being quick on my feet to respond to any yaw faster than anticipated. I found it was more a relaxing of the right pedal for a slow turn rather than a lot of pressure on the left. Sounds to me the student went solo a bit early or wasn't trained accordingly.