FireLance
Legend
If it still bothers you, think about it from this perspective:
Character A is not moving himself. Hence, he does not have to split his concentration between moving himself and defending himself against his enemies. It is this lapse in concentration that normally allows an enemy to take an opportunity attack. Since he is being moved, he is able to concentrate fully on maintaining his defenses. Therefore, he does not provoke an opportunity attack.
Character A is not moving himself. Hence, he does not have to split his concentration between moving himself and defending himself against his enemies. It is this lapse in concentration that normally allows an enemy to take an opportunity attack. Since he is being moved, he is able to concentrate fully on maintaining his defenses. Therefore, he does not provoke an opportunity attack.