The religious leaders were afraid yes, but am of the opinion it wasn't out of a sincere heart for the people, but to protect their own rights and privileges that came with their position, it could be that they were expecting that God will confer with them to let them know His plan exclusively, or they had cast off restraints and merely going through the motions of life and not expecting the MESSIAH. Secondly, John must have been moved by the spirit to answer them thus, else, they could have stopped him. He had a good grasp of who and what he was called to do and rightly so. If he didn't he could have been distracted by being compared to Elijah, he probably did not even know he was. He just stuck with his purpose as explained without questions by the Holy spirit.