I have a feeling that he'll do fine. He did the ethical thing, and I assume exercised the care and follow-through that a similarly educated and trained person would find prudent.
Not sure how the airport will fare, there are good arguments on both sides. Does the public have a right to expect defibrilation facilities? Does the airport have a legal duty to provide them? What are the ramifications of providing a feel-good impression without the ability to deliver the help? Similar to the impression that police presence gives, that they have a duty to help a person in distress, yet crime victims have no recourse aganst a police department for failing to prevent crime.
Philadelphia Airport is plagued with the same problems as the city itself. The woman brought in by Mayor Street and his people to run the airport left after they found out her "Harvard" degree was a dream. The link between city hall and who owns the
business areas of the airport have been well publicized. The trial going on now in Philadelphia spell out the strange deals and payola environment. We use BWI and ignore
Philadelphia
Laws are different in different states, but generally, even if an entity is not required to provide a service, if they choose to provide the service, they are obligated to provide it properly. I don't know if there are any regulations requiring the AEDs to be available, but even if there were not required, the entity choosing to place them there assumed a duty by providing them. The doctor should not be liable, because he did not have control over the equipment.