Well the Knight is moving back and forth and the Rogues are using that movement to predict its' future position linearly I think.
You would need some pretty serious math to be able to know where the Knight will actually be in the future when it is affected by gravitational pull or impulses changing direction.
Or you would have to add some weird game logic that would make Rogues aim at the center of the blackhole when their target is affected by it.
But what happens if there are several overlapping blackholes?