As sheer Rambo style speculation I wonder whether one could design a small shaped charge that would pierce the top of the cabin with minimal damage therein and then rapidly release fentanyl like the Russians used in their Moscow hostage crisis. With SEALs pre-positioned for prompt boarding to save the only one who counts. The fentanyl did work well enough then; the problem was it worked too well. With just one to save and having the benefit of the Russian experience it might be workable IF the technical problems could be overcome. We might even be able to keep the details secret as there are no media on the scene, SEALs won’t talk, no terrorists need survive, and the rescued hostage doesn’t need to know the details. If only we could keep the WH out of the loop...
What if EVERYONE simply left. The pirates will not gain by killing the hostage. But never give them ransome money. Then the hostage has no value to them.
Use BZ instead. Unfortunately it is likely that the effects must be instantaneous so lead is the only option. Sink the boat and put them all in the water.