Argument in favor of the characters behaving realistically

I tried to do this the other day but handled it very poorly. I think the argument many people make that the characters behavior was unrealistic is a very weak one. I would like to issue a FRIENDLY challenge, in the spirit of open debate, to anyone who feels otherwise. Please respond to these two points and offer better evidence in favor of the characters behaving unrealistically.

A) The way characters react to imaginary sci-fi scenarios can only be
speculation based on the closest similar situations which have happened
in real life. The way people have reacted in similar situations doesn't
prove anything, but it is the best clue we have.
If you disagree on
this point, your responsibility in the debate is to let me know where
you think we find better clues about how people would behave in this
fictional situation.

B) We do know for absolute certain that when
people are under extreme duress their ability to think and behave
logically can be severely compromised almost immediately. They often
will go through wild mood swings consisting of extreme highs and lows.
Their behavior becomes erratic. In fact, it's surprisingly common, even
in exceptionally intelligent people trained to deal with the exact
situation that's fucking them up. This has happened many many times in
recorded history - to soldiers, to police officers, to doctors and
surgeons. The record of evidence describing these situations is
extensive to the point of being irrefutable. If you insist I'll prove
this to you.

I think these two points make a pretty good case for
realistic behavior. I don't know if I'm right. But if you disagree you need to respond to those two main points and explain why you
think it would be more realistic if their behavior was consistent.