With the force of the Lorcar psykers the planet was slowed to a stop as it neared their system. However...They thought that it would prove valuable, and so they used their psychic power to pull it into their solar system. Maneuvering the massive planet took all of their concentration; telekinesis was a strong ability, but they were moving a planet. Even the Hornet Queen could not pull it off alone, so the rest of the Bioships pooled their psychic power to give her the strength to first stop, then move, the planet into a proper orbit close enough to their sun to support life. They'd check it out later; first, they needed to secure it.
And then...They saw the other ships there, trying to take their new possession away from them. The Hornet Queen moved towards their new planet, flanked by the rest of their fleet. While they couldn't use much psychic power right then...They had other abilities. Like missiles. And, if it came down to it...They would go into a direct melee against the invaders, stabbing through their hulls. But first, they'd see if the invasionary force decided to continue...They'd be allowed to leave, just this once, if they could escape the coming swarms, but if they persisted, they'd be devoured, survivors taken for the swarm to learn how these metal ships worked...To then take them for their own.