They can't do anything but come down hard on him. If the incident passed without repercussion, it's logical to assume it would be repeated - if not by this particular chap.
Rubbish.
You don't trash an expensively licensed person for something like this. Well YOU might (which is why you aren't a manager!
)
The investigation will (in all probability) read "Operator suspended during investigation.
(Normal, and good safety practice as the person under investigation is always under stress. Suspending them from duty removes the organisation from suspicion of forcing a controller to operate under stress, and makes them available for interview without delaying the investigation.) Investigation determined operations never occurred without a licensed ATC operator online. An unlicensed person made five radio transmissions, while supervised, which was in accordance with training practices.
(although this instance was outside of the training programme, and was unauthorised in this instance.) Operators have been briefed on correct practices. Case Closed. Operators re-instated."
The problem is that even if the kid had started joking around over the radio, the pilot is forced to do exactly what he says.
... if any proof were needed that trolls are on PPRuNe! ..