No, it's prejudice to decide, beforehand, that he WON'T do his own thinking. After he speaks, to then conclude that he isn't doing his own thinking, based on his words and actions, is not prejudice, it's fairness. Prejudice means to PRE JUDGE. If you judge them after the fact, it's not pre judging them.
Yes, but when you demonstrate the inability or unwillingness to deviate from the already established position, and you do so in statements of absolutely, it's a clear indication of restricted thinking, of failing or refusing to consider other viewpoints, an indication of a closed mind not open to alternatives.