Reality is that the flight crew made a decision to conserve fuel and not run the AC.  Hot air coming in does nothing to cool an airplane.  I'm betting there were adults on that flight that were near heat exhaustion at the end of two hours on a hot airplane.  Had I been flying with my 91 year old mother I'd have been panicked at that point because while a normal flight would be no problem I know she would not have been able to handle heat exhaustion at her age and with her health conditions.