Of course, what the Father should have done is to hold child down by force , tighten the seatbelt as much as possible and then keep the child pinned down into the seat no matter how much it screamed and fought back. At 36 months, it should damn well know better.
Without doubt, the passengers on the aircraft and a number of posters here, would have fully understood and approved of this action. Inevitably, there would be complaints about the noise but that could be dealt with by even firmer action from the parent perhaps by administering corporal punishment - liberally if necessary.
Quite frankly, it's the only way they'll ever learn how to behave.