A requote from earlier in the thread:
regarding seling the diet milkshakes...
did it occur to any of you that he was using the product himself and somehow got a very low blood sugar causing this odd behavior? an aviation medical examiner from Chicago suggested that low blood sugar could cause this sort of behavior
Talking with a friend who knows Captain Osbon, it appears he was indeed taking the supplement and hawking it to his coworkers at JetBlue. As is often the case with other episodes of abnormal pilot behavior, colleagues noted changes in his mood and affect prior to the inflight outburst. The company was notified but apparently did not take action at the time. JetBlue pilots are nonunion, not sure if they have anything like ALPA's Professional Standards committee to help mitigate personal issues before they reach the disciplinary level.
Of course, these observations are all with the benefit of hindsight, as with any case of someone who is acting odd, but not yet dangerously, it is a tough call of whether or when to intervene as a coworker, family member or employer. An example discussed earlier here is Auburn Calloway, the FedEx 705 hijacker. Looking back, there were multiple signs that Auburn had lied and acted unusually before the hijacking but little was done to remove him from the flight deck.
Auburn Calloway was unsuccessful with his plea of temporary insanity. Some years later he claimed that he had an undiagnosed sleep disorder and that (among the customary other reasons) was why the FDX 705 hijacking trial was unfair:
Today, in calls and letters to USA TODAY, Calloway says his trial wasn't fair. He blames his attack on a sleep-related malady.
"None of the mental health 'experts' at my trial had the requisite experience in sleep medicine pathology to have discovered the 'mental disease or defect' I labored under during my uncharacteristic behavior on board FedEx Flight 705 in 1994," he said.
USATODAY.com - Inside the minds of workplace killers