if Stuart_Armstrong had mentioned that he was just talking about the historical record, there wouldn't have been a need for steven0461's comment

That demands seems a little strange. Should he have disclaimed any claim about future warming? But given past warming caused by human CO2 (and other) emissions, we should expect more warming if we continue that activity (actually, the IPCC thinks warming would continue even if CO2 were kept at current levels).

On the other hand, I'm not seeing any way to read Stuart's statement as anything like, "if your estimate of future warming is only 50% of the estimate I prefer you're irrational."