I have nothing against metric per se as it works well with currencies and temperature. I just feel that having everything metric is a kind of dumbing down. Stones and feet and inches work perfectly well.
If a document were being produced for him or by him would you think it reasonable for it to describe lengths, areas, weights, volumes and so on in imperial units? For my money it would be so laughable that I seriously thought the original article was a spoof.
I cannot bear hearing people say, 'Can I get...' when ordering food. It should be 'May I have...' as manners are important IMV.
What does this have to do with anything? We're discussing the language to be used by his staff in official matters.