The inverted AeroPress method places the brewer upside down so the plunger acts as a seal, preventing any liquid from flowing through until you are ready to press. This gives complete control over steep time.
Standard AeroPress brewing lets some coffee drip through while you steep, which can make the cup unevenly extracted. Inverting eliminates this variable entirely.
Brewers who want maximum repeatability. The inverted method is easier to reproduce exactly than the standard position.