> For my part, I want to use that freedom to tell people that it is unproductive and generally considered rude to make unsolicited, uncharitable, and uninformed assumptions about the marriages of others. Moreso, because I think are giving out factually bad advice.

Perhaps you should respond to the factually bad parts, because that's actually debatable. Leading with "that's rude" is a personal sentiment and all it takes to rebut that is a "no, it's really not".