I heard the events described in the original posting of this thread and fully agree with the controllers displeasure at the "guard police".
It was obvious that the lost student was under considerable stress, and the controllers' attempts to assist were hindered by these individuals.
I agree that accidental transmissions on 121.5 block the frequency, but only for a very minute percentage of the time. Far more damaging are the constant interruptions when assistance is genuinely required.
"Guard police" are a pain in the neck, and should realise that they may not have the full picture when carrying out their constabulary duties.
Well done to the controller concerned for dealing forcefully with these interfering individuals at the time.