This is my second game with V2.0, the first was on an immense galaxy where I didn't notice this behavior, and this game is on a medium galaxy. Note that there are 6 pirate bases placed close together in the bottom left of the map:
I've explored most, but certainly not all, of the rest of the galaxy and found no other pirates at all.
Has anyone else seen this? Maybe I've just hit a really bad random number generation for this map.