Obviously super dumb letting the kid anywhere near the controls but he didn't "let him pilot" the plane.

The aircraft was on autopilot and the yoke was locked. The problem was the pilot didn't realise a particular quirk of this aircraft is that autopilot is disengaged if a large enough force is applied to the yoke. He also didn't realise his son was puling on it with that much force.

It was a very stupid and very avoidable accident but he wasn't like "hey lets see how the kid does as a pilot". He let the kid sit in his seat whilst he got up to talk to his wife or stretch his legs or whatever and next thing, the kid had disengaged the autopilot and put the plane in such a manoeuvre that the G forces stopped the pilot from ever being able to get back into his seat.