<<what protection is there against some kid with a handheld VHF pretending to the the Tower?>>
None and, in the UK, no restrictions on buying such equipment. I was involved in a loss of separation when someone with, presumably, a handheld transceiver issued "instructions" to traffic I was controlling. It is not funny. When one of my sons was young I took him into a control tower while I was working and he had strict instructions to keep well out of the way and not to touch anything. As for letting a kid talk on a busy ATC frequency - it's lunacy and I don't think it does anything for "professionalism". Would pilots be happy to let a kid sit in and fly their aeroplane? Ooooooppps.. sorry; it did happen once, didn't it? And a lot of people got dead all of a sudden.
Next time you have a surgical operation, think to yourself: "Wonder if it's the surgeon's kid doing it?"