Jose'.Marti was engaged in a large scale battle against Commander Casero and a Freelancer by the name of Alvise Kinnara, as well as multiple other Pirate ships. The Freelancer in question and Commander Casero ended up dispatching them all, if the video feed I was given is correct.
Why should he be left alone simply because he saved one Navyman's life? He has probably killed much more than one.
One life is not worth many. No matter who the person.