This is a Random Event. Occurs in:
You're surprised to find a ship without Slug markings stranded all the way out here, and move in to provide assistance. When you see the pirate insignia on the hull you quickly reconsider.
- Fight a pirate ship (default rewards).
- Keep your distance and hope they haven't seen you yet.
- Nothing happens.
This event is called "NEBULA_SLUG_PIRATE" in the datafiles.