What is the point of saying "I warned my comment would sound vituperative"? Acknowledging a flaw in the motivation of your comment doesn't negate that flaw, it

What is the point of saying "I warned my comment would sound vituperative"? Acknowledging a flaw in the motivation of your comment doesn't negate that flaw, it means you realize you are posting something mean spirited and consciously deciding to do it even though you recognize you're being mean spirited.