It's a great question because if it draws out a rude response like yours, the questioner knows to not waste more time on small talk.

Would you really accept being asked my imaginary question about your spouses sex life from any ordinary aquaintence? Why not? It's free help! You should always want your spouse to have as full and rich a life as possible, and it's too easy to forget that a big part of their life is actually subject to your level of effort and imagination and bravery.

The original question is essentially personal on the order that we usually place on sexual or health matters.

The best word is "inconsiderate" in that it literally fails to consider, or considers and ignores, that many, perhaps most people's honest answer would have to be no, and further, the process of being asked and answering forces everyone who had to answer "no" or "not enough", to recognize that "no" isn't just a harmless answer like what flavor of ice cream you like, where chocolate or vanilla or "I don't like ice cream" are all equally fine. No they are forced to confront that "no" is a failing, and therefor that they fail at something, and that what they fail at is nothing too important, just life itself.