Geraufl must be able to stun you as part of a scripted event that completes the quest. If he is grayed out then he might not be able to hit you, preventing the completion of the quest. To remedy this, mentor down to level 35 and don't use any one-shot abilities. Just aggro him and he should stun you soon after.
Good-aligned players can still complete this quest, even after mentoring down to a lower level. Just make sure to kill all the guards from the Chronomages located on the Freeport Docks to the entrance of the instance.