Well, that depends on what the premises and conclusion were. "That's your opinion" can be used as a deflecting move if someone doesn't want to have a particular debate at that particular moment (e.g. if the premises and conclusions were about something highly charged and the woman was not interested in having a highly charged debate). Ignoring a deflecting move could be considered a social blunder, and maybe that's what the woman was responding to. There are a lot of ways to read this situation, and many of them are not "haha, look at how irrational this woman was."