Is this a "Let he who is without sin cast the first stone" objection, where even the slightest bit of hypocrisy or impurity justifies rejecting the argument? I

Is this a "Let he who is without sin cast the first stone" objection, where even the slightest bit of hypocrisy or impurity justifies rejecting the argument? If a vegetarian, who became a vegetarian because of the high environmental impact of meat production, berates you for defending data center water use, would that convince you to change your mind? What about a vegan, who also stopped flying and doesn't drive, and is organizing a protest to shut down the local golf course?