Yeah, that's bullcrap. If the pilots were concerned, or the dad wasn't telling his son every single word to say, then it could have been dangerous, but as it was it was perfectly fine. And as for professionalism... what? This was purely between employees, meaning that any unprofessionalism wouldn't even necessarily have made it out of the cockpit. Beyond that, my impression of flights is that friendliness takes priority over professionalism when dealing with customers, meaning that even if this was a public thing, it shouldn't be a problem. This is stupid.