These NPCs have been in the game forever and there are sections of space specifically to PvE farm/engage them.

Some of the articles point out this added to the initial confusion in the early waves of the attack because it was already an existing strategy for a player to get a (small) fleet of these NPCs following them to a station (either for the station to help pick the fleet apart for easier farming, or to annoy the station of a neighbor). There was an early question apparently if some players had found a way to get larger than usual fleets of the NPCs to follow them in that previous manner.