re: He was under fire earlier that day, not when picking up the people from the #3 boat
Frequency is key to your unstated question.
Under fire is not necessarily every second or even every minute.
This quite frankly is as silly as your everyone is in danger answer elsewhere.
You seem hell bent on making Vietnam a cake walk for Kerry.
It was 90 minutes of hell.
Kerry chose to go where people were being shot and blown up and he again chose to return there and even if he originally thought to a "reasonably save" job he stuck to it.
He could have chosen the cowards way out and done exactly what Bush did.