I think they were selfish and bad parents. Calling them naive allows that they simply were innocent and stupid flies in the face of their chosen careers and education. These are not pizza dilevery men. The friends of yours who had to consider and did I would go as far to say the same about them.I can't imagine leaving my children home alone for 5 minutes, much less for days on end. In that manner, I think the McCann's were ridiculously naive and stoopid.
My sil did this kind of crap, a great deal. No physical harm came to her kids but they are now and have always been selfish, bad and selfabsorbed parents.