As a professional pilot, I can see both sides of teh argument based on how busy a day it was. All airports have busy days and not so busy days. And at places like JFK, ATL, LAX they have certian times of teh day that are busier than others called pushes... so if it was a super slow time what is teh harm?? If dad was there with his own headset on, no biggy. BUt when radiop chatter is so bad you cant hardly get your calls in, this wouldnt have been a good idea, and runway incursion is a big problem, and if something had gone wrong with this kid running tower frequency....Cluster F*ck...
Additionally was it a VFR day where the weather was super clear or were all the planes shooting ILS to minimums???