First AA is at fault for catering and maintenance. There hopefully wouldn't have been a delay for a mechanical. Since there was the mechanical problem, there really is no justification why the plane wasn't catered: Catering should have occured before/during plane boarding or while the the plane was at the gate for 1 hour on their mechanical delay. I get that mechanicals happen but don't get why catering would be delayed at AA's hub and HDQ city unless there were tornado warnings that wouldn't allow catering trucks out.

Skedaddle as quickly as possible, yes, but the pilot could still have used a little more common sense to provide good customer service. The pilot should have considered that his first class would not have brought food as they expected to be served and for some of them, especially elderly or diabetic, this time without food (the flight plus the hour for mechanical) could be a real physical hardship.

All in all, AA should reimburse OP for the upgrade.