It seems to have many of the same digimon that have been attacking us as of late. This could be where they have been coming from and taking the castle could prove useful in that aspect. Also, based only on what we have observed from outside I can only come to the conclusion that answers to our questions can be found within the walls. We cannot get inside without being seen which means we have to take a more active method of entry.

Besides, I have a feeling that these rabid digimon, if they continue to increase, will eventually wander away to other villages and areas, going back to my first point.