SIDSTAR,
The captain was not stopped from doing what he should have done. The authority of the commander cannot be overridden. He took a decision not to evacute the aircraft with a bomb on board threat. The final say in these matters rest solely with the aircraft's commander. He is the one that is legally responsible and accountable. If the situation turned nasty and there was a loss of life, he would have been held responsible.
WHy he failed/ refused to let everyone off the aircraft at this stage is speculation and conjecture, but I would love to know.
Anyone remember the Tristar at Riyadh, with a fire raging on board, where the muppet in charge, after landing taxied slowly off the runway to facilitate the imminent arrival of some rich geyser? Poor decision making cost everyone on board their lives.
I fully agree with Rollingthunder - if I were on board and aircraft with a bomb threat, I would not remain quietly seated whilst the muppet up the front pondered life.