IAH-OIL-TRASH

To OP: Even if there was NO problem w/ the cargo door, the flight may not have been allowed for take-off anyway seeing the evidence of delays at your destination. Blaming the departure delay on a cargo door malfunction may be in error. If they were cleared to take off and there was still a problem with the cargo door, then you can blame a cargo door malfunction for the delay. Do you have any proof your flight had permission to take off prior to the door being fixed? Planes actually don't take off any old time they want. They can be delayed at their departure airport until conditions at an adversely-affected airport clear enough for aircraft already in the air can land and grounded a/c to take off. SFO doesn't have the number of runways to quickly clear out a backlog of slots. It does look like the PRIMARY reason (and maybe the sole reason once the door was fixed) was aircraft being held at their origination airport. Stuff happens on the west coast that you can't see out your window in the east.