Especially when facing lower skilled players I found it more helpful to recognize the tendencies rather than trying to understand their reasoning. In this case you can make a mental note that he will call cbets in position with an underpair on a dry board and continue to pay off on the river when a scarecard hits. These are the things that will help you in future hands.
Thinking about what this call tells you about his image of you, or his own mental state - that's all fluff that is not going to help you make better decisions.