Again, suppose it were like this: people-seeds drift about in the air like pollen, and if you open your windows, one may drift in and take root in your carpets or upholstery. You don’t want children, so you fix up your windows with fine mesh screens, the very best you can buy. As can happen, however, and on very, very rare occasions does happen, one of the screens is defective; and a seed drifts in and takes root.
The analogy is very laughable, but let's consider it at face value. You open the window, well aware of the risk. Then, the "people-seeds" take root.
Here comes the problem. Thomson says you would then have the right to remove them from your home. She made the same mistake in the violinist argument; she confuses negative rights with positive rights. Following this analogy, all that could be done is induced labor. For an argument against induced labor before viability, see the boat analogy.
So, to imporve the analogy, let's say that the people seeds plant, and one comes up to you asking for food. You then proceed to poison her, or dismember her, or burn her, or... you get the point. You would then rightfully be charged with murder.