Those four are a good representation of what a normal person values. I guess his inability to expound on why is because of the type of questioning. It seems to be a deep conversation but the answer appears too simple a reply. If a person is asked why they value their family highly, they will also be speechless. These are things that are not usually put into words. They are my blood, they make me feel happy and loved, I love them, etc. These are obvious things that everyone expects the one asking to know. So answering something other than this is what could cause some the speechlessness.
It is hard to answer, because we don't necessarily think that deeply on it, even though we might act in ways that express it. We can show love, without knowing why we do it, but perhaps it is good to take a step back occasionally and ask the question.
I guess that's true.