I don't think this guy has any problems outside of him not thinking through the consequences of his choices. Sometimes the good idea fairy pops up and whispers in our ear. Most of us think "that sounds great, but is getting fired really worth saving 5 minutes in line or bringing my liquids through?" I am guessing he didn't.
The guy is an accomplished pilot and has a strong record in and out of the service. I will give him the benefit of a doubt. Sounds like he knows what he did wrong and is now ready to pay the piper. Thankfully for him, his career in dentistry should be just fine. I am guessing he will pay a fine and maybe do some community service.
As far as being let go by Cathay, who knows what happened there? Their culture doesn't sound like one that I would do well in based on what I have read. Maybe he just didn't fit in.