I found the clip funny, and it must have been infuriating for Kery to answer that "Science" line of questioning.
But the problem with this guy is on whose behalf he is dumb. Someone wth shit-for-brains, like him, hasn't actually fond that data on 2-million-year-old CO2 levels by himself. He has been fed it by the actual ruling class - the donors who have a vested interest in blocking climate legislation. And the fact is, he would be taking the same position, with maybe some more disguise, if he was Einstein but had the same donors and same voters.