Another way, if cripple skills are not available, is to kill the boss Commander Werishakul at the end of his path show above. The 'Sneaky Corsair' will then have no target to get in contact with. Running through the path killing all the obstructions moves the contact counters (quest markers) well past the double bridge bottleneck so he will actually start very close to the end, as long as the boss is dead you should have no problems completing this quest.