It’s one thing to run a safehouse and allow alien invaders to stay overnight or for a few days. It’s another matter to allow them to stay for months at a time. The logistics change completely when Pedro and family are hanging around for a long time. A safehouse has to present an appearance of normalcy, and that ain’t gonna work with 10 families living in a house.
So many pathogens await the opportunity of hosts crowding into a confined space.