It's not just AA that we all should be wary of. It's the public transit system all together, by either boat; plane or train.
You must look at it from there point of view too. How do they know that this dog isn't reacting to something else and not just the temperatures or stress? In their eyes, no doubt, there potentially was something more dangerous going on w/ the dog that could effect people too. In either case, this is terrible that it happened, but we shouldn't be so one sided to say what they should or should have not done. WE all can assume it was from the temperatures that this English Bulldog was suffering from, but we weren't there. I'm sorry for the owners, to know their dog is right around the corner and cannot help him. This is terrible, but I'm sure the airlines too did not want a dead dog on their hands. They did what they thought was right and unfortunantely a life was lost because of it. Policies are what assist in keeping us safe and they were just following it no doubt. They aren't vets themselves and common sense "can" be a dangerous thing in those situations.
RIP little guy.