This passage comes after 2 passages about Pharisees and Sadducees asking their pet questions to Jesus (Render unto Caesar and Resurrection). Following his answers, this scribe comes with his question. Like the two prior questions, it is a sort of test. What the scribe has in mind exactly, we don’t know.
Regardless of the scribe’s motivation, Jesus has an answer, and a well grounded answer. A basic answer. And an answer that we still struggle with. Now Jesus has everyone’s attention. Jesus 3, religious authorities 0. So from these responses to pointed questions, Jesus moves on. With everyone’s attention, he rewrites the expectations of the Messiah to be descended from David. Jesus comments on the scribes and their behavior. And then Jesus comments on the behavior of a poor widow. The same kind of poor widow that scribes were devouring.
What would Jesus tell us if he had our undivided attention? What would Jesus say if he had refuted the experts, and became the expert in our eyes? What would he say once we became ready to listen?