Ha, that's actually a good idea and pretty funny. Imagine the "pirates" waking up to find themselves moving ever closer to the Navy ship. ("WTF?") And when one comes out to try to cut the line, as they surely will, a sniper takes them out.
That’s creative. I like head games myself. Stage a “bigger fish swaller.” That is, send out a phony ship of some sort that claims to have attached explosives to the pirates’ craft. Have them announce that if they are not paid $2.5M, they will blow up the original batch of pirates.
Then you tell the pirates you will save them from those lunatics if they release the captain...but you have the cash and the bigger fish wants it all and a little more, and what can you do?
At the very least it’ll distract them and wear them down. :)