On one hand, there really was an SPD politician who made that claim, but it was current party chairman Kurt Beck.

On the other hand, I find that the below referenced Öko-Institut numbers come from a study asked for by Gabriel's ministerium (the full study is here (pdf!)), which looked separately at CO2 per 1 kW electricity production and combined 2kW heat and 1kW electricity production. Only the latter comparison shows only block heating gas as better than German nuclear+oil heating, so I think Gabriel shouldn1t be the person arguing for coal beating nuclear.

_{*Lunatic*, n.
One whose delusions are out of fashion.}