I don't see what difference it makes how they chose to use their property--whether for construction, storage, or sleeping. All that matters is that it was their property.
You don't know, apparently, the long history of the law on this point. The law makes a huge distinction on moral grounds between your rights to use force, especially lethal force, when protecting YOUR OWN LIFE or the LIFE OF OTHERS versus mere property. I suggest you do a google search and find a nice dissertation on the subject.