Indeed - the implication that a statement merely containing anything factual or backed by evidence makes the whole thing uncriticizable ("but it's true") is maybe the most common fallacy made in defense of provocative statements.
"Delete the whole" is not how threads work on HN. The way that threads work on HN, assuming that they're on topic, is that people should post intellectually curious comments and avoid posting unsubstantive or predictable ones.
Edit to match yours: If this convo is so fraught, Dang should delete the whole thread.