Well, I don't see why they can't do the same at the place they're at now.
They could, of course.
All things being equal, however, I think thick concrete walls surrounded by trenches and barbed wire are a better bet for long-term survival than a few suburban homes and a thin wall made of sheet metal surrounded by the same.
I think it is easier to monitor a smaller area. A prison is good, but not impenetrable either, as the govna proved. All he had to do was drive a truck through the fence. A fence always needs repairs and is probably easier to penetrate. Also, I don't think those walls are "sheet metal." I think they are solid steel, and they look to be quite thick. With a few adjustments, I think they could make it a very safe place. That's just my opinion though. I would stay there and try to beef it up as much as possible. Move the supports to the inside, they could even double up on the walls. They could put a fence with barbed wire around the walls that already exist. I think there are a lot of things that they could do instead of taking the chance of moving again.