I am not the mod ...in question, but I can probably give you my impression on why your answer was deleted.
On this site we have basically two major problems that we need to solve in order for the community to be functional:
We need questions to be based on specific, evidence based, largely believed claims
We need answers to be based on evidence.
The first requirement is to avoid wasting time, but also to avoid "how many angels can fit on a pin" kind of questions. Many controversial topics are controversial because they are hard to debate, and because the debate becomes an argument on personal values and beliefs and not on measurable facts.
Requiring the questions to be about factual, disprovable claims allows a fair way of judging answers -- by requiring them to present evidence, we can judge how convincing that evidence is, instead of focusing on the pure "truthiness" of the answer, which in many cases is a matter of opinions.
In this particular case, I agree that the claim is pointless: showing high CO2 in the past is irrelevant, it's cherry picking. But -- is it also a lie? That's what the question is about, the facts. A perfect answer would bring in evidence that the facts are true, but also that their truthiness is irrelevant, not because of logic, but bringing in the climate science context that shows their irrelevance. At a minimum, though, we expect a verification of the facts asked about -- your answer did not do that, but delegated it to DavePhd's answer and added common-sense based commentary to it.
This seems to be a valid reason to remove it, given how the site works.