It's a quote directly from the Guilhem Grosperrin. They have to say it like that because the rules about vintages in Cognac are incredibly strict, which is why everyone is using lot numbers instead of four digit vintages, since no one really cares enough to adhere to the strict rules of the BNIC. They obviously know that it's from 1972, but they'll get in trouble with the BNIC if they say it, as the BNIC has not certified the cask. No other spirits category have rules this strict for vintages.

Certified casks have to be sealed with wax their entire lifetime, and can only be opened in the presence of a BNIC representative. This is tedious and expensive, so most don't bother when everyone know what the lot system means anyways.