Shock! Horror
But the reality is that at some point of time the student is given an instrument in his hands and told to get on with it.
He/She is of course carefully watched and has seen how it is done.
Every brain surgeon was once a student
Same thing with every controller.
Most likely the suspended controller and supervisor have managed trainees and supervised them while they were on the mike. This student happened to be a bit younger and likely no less conscientious.