From the article:
"The transcript of the cockpit voice recorder showed the pilots joking,
swearing and yawning as the plane descended below 10,000 feet -- the point
at which the sterile-cockpit rule-comes into play."
Now, I'm not an expert on plane safety (though I know how to fasten my seatbelt, duck between my legs and kiss my ass goodbye, and how to use the person next to me as a floatation device, in the event of a controlled flight into terrain). However, I know from enough driving experience that when you're yawning, you're tired enough to lose concentration. Whenever it happens to me, I feel I concentrate more when I have someone to talk to, helping my mind stay lucid and my body awake.
So perhaps it's more due to the
"...incorrect airport charts given to the pilots, the lack of information about
recent runway construction and taxiway changes, and the fact that only one air
traffic controller was on duty that morning."
I think the real safety issue with cockpit chatter is that if it's required to prevent falling asleep, more pilots and copilots are needed to overlap the burden of responsibility, similar to the precautions taken for air traffic controllers, especially on long flights.