Another point "City Fan"...the minute this captain opted to land an international flight after dispatch denied his request to do so...took this situation way beyond "professional standards." IF there was a "safety concern" he would have landed this aircraft way before 7 hours into this flight.
I hope that you aren't a crewmember. The decision to land the aircraft at other than the destination is ENTIRELY at the captains perogative - it has NOTHING to do with dispatch approving or denying a request! They can certainly be consulted for input in some decision making processes, but have no more influence than that.
How do you know the "safety concern" started earlier? The threat, or safety issue, may well have arisen far later into the flight. To take the "visining" example: If I were a crewmember that was told that someone had poisoned (or threatened to poison) my (or another crewmembers) meal, I can see no alternative but to land the aircraft at the nearest practical airport. The sky is no place to be when potentially affected by any form of toxin.
Korrol - I've heard of it apparently happening, but never seen it in action. I would hope that cabin crew are smart enough to not incapacitate a pilot, but I guess it would be hard to ever really know.