OK guys - this one has a bunch of screenshots - I edited it down into just the chat windows. This was a heroic UP. The priest healer is Amberlee - she submitted the screen shots. According to Amber, the pallie tank was so upset that the shaman pulled threat that he made the shaman the tank in his raid frames, and basically switched to dps. The boss died, no wipes, and everything was ok.
I did not include the fallout from this. In the screenshots that followed was a tedious bit of douchebaggery that was primarily focused around why 5221 gearscore is a far superior player to a 5179 gearscore. EPEEN ftw!
So we have 2 forms of attitude disorder here:
"I'm a tank and you need me more than I need you" and "gearscore = awesome-sauce".