This argument is very similar to one being used against Robert Blake. He said that Bonny was afraid of someone stalking her, so he carried a gun to protect her. On the night she was killed, he inadvertantly left it in the restaurant and he walked back to get it. During that time she was killed.

He is criticised for leaving her alone while he returned for the restaurant. The argument is if he were so concerned for her safety why would he leave her alone? There are explanations, but at least in his case I believe it's a fair question.

In the Ramseys case it has nothing to do with the case at all. Had they professed fear for Burke and yet done NOTHING to add security, or perhaps put him in dangerous situations (leaving him alone in a park, store etc...) then it might have some bearing on their possible guilt.

Because they didn't take every precaution that on hindsight some people believed they should, doesn't mean they weren't careful and concerned about his safetey. This is an extremely weak argument on their part and a waste of time during this interrogation...oops I mean interview.