The product clearly isn't designed for people with J pouches. This is evident from a very superficial reading of the product's website which specifically mentions it is designed for people with colons in the "how it works" section:
"Your body relies on a bend in the colon (where your poop lives) and the anus (where your poop says hi) to keep everything stored until showtime. The posture of the western toilet causes a kink in this tunnel, which leads to major blockage. Squatty Potty undoes this kink so you can do business the way you were meant to."
How it does that is anyone's guess, but one thing is for sure, if you have a J Pouch you don't have a "bend in your colon", or a "kink in the tunnel." Sounds like it's designed for kids with colons, and by my estimate that's about 0% of the readers on this board.