I'm pretty sure he does say aft nacelle. Thing is a nacelle could refer to any engine housing on the ship, warp, impulse, fusion thruster. Refering to the impulse deck as a single nacelle (housing) would make more sense, the lift support systems buried in the neck part of the engineering assembly.
But Khan or not he's still shrugging off a ship to ship jump, 40 deck climb, hand to hand combat and a pretty hard stun blast to the torso. One or two words slurred isn't bad.