I tell you what, it is bloody lucky that this kind of thing doesn't happen more often. I have only been flying commercially for airlines for 12 years but the way the industry has changed is remarkable. I now have to put up with totally over the top security procedures on a daily basis, companies crying poor every day and constantly trying to cut my pay and conditions or threaten me with redundancy, threat of terrorism, increasing perception by the public that we are just button pushers and finally the increased instances of passengers being disruptive.
If you are already in a slightly fragile state due to 'outside' events I can see that along with all the above pressure you wouldn't really need a big push to make you lose the plot. It happened last month with the Cabin Crew Member that lost it, now we see it here with the Captain. Lets hope that the next event isn't actually in the flight deck.