You're getting downvotes because the target of this particular lie was a known liar, so people probably feel like it's some sort of poetic justice (or they know it's just in-kind retaliation and are cathartically satisfied by it).

I don't think the right answer to widespread disinformation campaigns is retaliatory disinformation campaigns (even if they're couched – pun not intended – in a just-barely-thin-enough veil of "wink wink we know this is a joke").

The right answer is to create systems and measures that actually limit disinformation.