The question is missing some key components like "at what distance/for what distance". But even then he's still wrong. The only time I could see that being even remotely similar is if you change from one cartridge with a specific bullet and weight with a certain powder charge, to the same cartridge with the same bullet, but a higher powder charge. But even then, the spin is wrong for what he is claiming.
When I was trring to find my accurate load for my 444 I used 300gr Sierra FP's and H4198. Varied the charge by 2gr (neither were at max). Unfortunately for me, I didn't label the base of the cartridges. I just figured I'd remember how I put them in the box. Turned out I was wrong. So I fired a round. Adjusted W&E, and fired another round. Low left. Adjusted W&E again and fired, high right. Took me a couple rounds (and some four letter words) to figure out what had happened. It wasn't anything mechanical like my scope bases being lose or my scope internals having failed. I simply wasn't feeding the same charged rounds each time. When I figured it out, I zeroed POA/POI to the higher charged rounds. Got great groups. Could cover them with a quarter at 100 yards. And my lighter charged rounds were hitting about 3.5-4" low and left with the same POA.
So here is my question for the other instructor:
If a bullet slows down as soon as it leaves the barrel, and gravity immediately begins to take hold, why would you ever "zero" a rifle to miss low?