> since there's no proof of his story, his story sits in doubt. Right?

Not for me. The author has more credibility in my eyes than any employee of the TSA.

> Is there reason for me to automatically doubt the sincerity of those who tested him?

Since they lied to him through the entire ordeal ("We’ll just be a few minutes, and then you’ll be able to go."), the rest of their declarations are equally suspect.