There is a Star Swarm queen in the homeworld system of one of my NPR allies. And it doesn't look hostile to them, in fact it only chases my own ships, and nothing happens if I leave the system. The NPR will occasionally shadow the queen with a few ships, but they won't shoot on them. The queen (and its offspring) is generally uninterested in any NPR ships or colonies.
I thought the Star Swarm was uncapable of diplomacy and hostile by default towards everyone else, is that not the case?