I think it comes from the fact that thoughtful people are slow to commit so long as other options are open. On the other hand, if they feel it is a true emergency, they also will move with insufficient information (as you say, that comes from millions of years of survival).

Most people tend to attribute their own thoughts and motives to others. That being the case, when someone becomes outspoken and passionate, even thoughtfull people tend to believe that they must have a good reason to be acting that way.

The thought is often "well, maybe it is an emergency -- and I am just missing something!"