It seems to be a variant of Male Answer Syndrome, and it goes like this: Person A asks a question about how to solve some problem. Person B is a total expert in subject matter closely related to the question person A asks, but not in the area required to specifically answer that question. Person B now "answers" person A's question by explaining how to solve some other problem which does lie within their area of expertise, despite the fact that this is obviously going to be of no help to person A.
Is there a term for this? If not, I'm thinking "insidious expertise".