There will be people who have a very in depth understanding of the actual events and circumstances in this case. As with many of the other readers and posters here, I am not one of them. However some of the issues raised lead to very polarized points of view. Perhaps it is time to take a more sideways or lateral viewpoint?
This type of event is very rare. Pilots, Captains and First Officers as well as Cabin crew and the passsengers in their charge are human and therefore subject to the occassional failures, illness and breakdowns that sporadically occur within any cross section of a society. There are procedures and checks and balances that seek to minimize the risk that even these rare occurences might bring, however in an imperfect world they can never be totally eliminated. In extremely rare cases "accidents" and serious incidents have resulted from physical, emotional and behavioural breakdowns that range from suicide, through depression to mental breakdown and exhaustion or simply the spectrum of fatigue.
One of the primary checks and balances in place, is the use of multiple system redundancy protection. In the human element this involves the use of more than 1 crewmember who can assume the mechanics of a particular role. When a failure occurs, it is often the case that the individual is carefully monitored rather than isolated as the best cause of action. Resource management is about the careful management of what is available, rather than establishing a hierarchy or pecking order for no particular imperative.
In a situation where the emotional behaviour or any other serious aspect of the health of a person, is having or is likely to have a serious impact on the safe operation of that flight, it is entirely proper that the best place for that aircraft is safely on the ground. Arguments about who did what to who, and the commercial implications of the chosen location, or the cost and inconvenience can then all be addressed at leisure. Although the behaviourial elements are a part of everybodies conscious existence, it is very rare that they overspill into an event such as this one. The matter will no doubt be investigated and where necessary the lessons learned and the treatments or rectifications will be applied.
However inconvenient, unusual or disruptive, the decision to prevent a bad situation (from whatever cause) escalating, or having the serious potential to escalate into a much worse one cannot in itself be faulted even if the person responsible for that decision is themselves the cause, or contributory to the causal event.