No, you misunderstand his (rhetorical) question.
He means that why is it that when Labour lose (or are held to be at risk of losing in) places where they have held for a long time but are now quite different from what they were once (meaning that the lengthy tenure is basically archaeological),* that sort of language gets used, but when this happens to seats long held by other parties things are phrased differently. It's a fair point.
*As he won't mind me pointing out, he even lives in such a place.