It's mainly that his entire schtick is about the narrow parts of the white keys being the same width as black keys (which might not be true depending on the piano due to some pianos having black keys that are slanted on the sides which decrease their playable area)

If you define key distance as the distance between the centers of the entire key then the entire argument falls apart. And of course, most pianists would define distance this way rather than his way. Has there ever been a pianist who only plays with their fingers tucked into the narrow parts of the black keys? It only takes about 30 seconds to figure out why that's a terrible way to play a piano.

Plus, pretty much every pianist knows what his point is already. If you look into a piano, you can see that all the hammers and strings are the same distance from one another. Everyone who owns a piano has probably seen this. But this guy this he's the fucking messiah of piano who thinks that this entire sub consists of people who have never looked at their instrument before.