I got to thinking, and I've never had an only child or a child whose siblings were not very close in age. My kids will egg each other on, and I am convinced that makes it easier for them to disobey (try to get away with something) or to do things that a single child may think of, but not do. Most of this stuff happened before they were teenagers, of course.
Yes ; I view this as a safety thing. To me it shows that the Hormans are careful parents. It would be concerning to me if Kyron had been known to wander around outside unsupervised while his parents were sleeping early in the morning. Not that the parents would be sleeping late ever, with an 18 month old in the house...
All JMO