Sadly this could easily be a thing that someone actually did, if that someone was a narcissistic abuser; they typically have the emotional maturity of a young child. It's likely a CYA move because the deception actually did not have no consequences, so the abuser decided to strike first. They all do this shit. The very second they are called on their shit they whip out the nukes to try to make the other person look like the perp.

And yes, to any reasonably-rational, mature adult, this looks like utter nonsense because to us, it is so easy to see how immoral and unethical this is AND how it is likely to backfire.

That isn't a complexity of thought or self-reflection this type of abuser engages in. They just want to win at all costs. (Remember that guy who was recently living in the White House? Same deal. What we have here is a child in an adult's body, and that child is angry because the other kid doesn't want to play in the same sandbox anymore now that our perp child has been mean.)