Unfortuanately it's a natural, human reaction to 'try and help'. Although not condoning it (I'm as appalled as you) it's going to happen when you have people fulfilling a position without the background knowledge and training that those of us in the 'professional world' have.
I would suggest a quiet word to both the instructor and the A/G operator, appraising them of a) the legal consequences if they'd got it wrong, and b) maybe a chat session informing them of who would have been in a better place to render assistance (adjacent ATC with radar, or even D&D on 121.5) than themselves.
If they don't take it on board then there's little else you can do - but you might be lucky and prevent it happening again.