The problem with making unreasonable demands for data in response to casual discussions is that it is usually done when the person strongly disagrees with the statement. For that reason, it is implicitly a counter argument, and a hypocritical one: "Your opinion differs from mine, so you must provide data to back up
yours!". None of the available options can be considered default, so any outcome is equally "grand" and subject to same requirements. Opposing without having a standpoint could happen in a peer review for a paper, but that is not what this is.
Your response is more reasonable, and is also more out in the open about the alternate belief (of course equally without data). Nothing wrong with disagreeing - only about making up unbalanced burdens of proof in casual discussions.