Well, what he didn't tell you is that one generally sees in the ice cores that CO2 lags the temperature by typically a few hundred years, not vice versa! (sciencebits.com)
If the observation that CO2 lags temperature by 800 years is accurate, then debating short term variations of atmospheric CO2 when compared to short term temperature variations of that atmosphere seems pointless. (joannenova.com.au)
We see very clearly that CO2 lags the temperature increases and has done so many times. (collective-evolution.com)