I like the idea of using meters and kilometers because they are more useful life skills in Canada.
Unfortunately I think this guy's argument is really pointless. He scans and presents a couple of maps to show that one size of grid works and another doesn't. He has complete control over the scale of the original scan and can make it show anything he wants. He can place the grids anywhere he wants. There is no 'real world case' presented here. The examples he scanned were scaled to fit publication and then potentially scaled again by him.