I'm not convinced that the change in posture has a significant effect on the ileocecal valve. I do understand it is more natural to squat, but just don't see how sitting would cause the valve to relax more.
That being said, I did try it and I took of my pants so I could squat on the toilet (seemed dangerous to have my pants at my ankles). I wouldn't try this at home, I think it only worked because I am young and nimble.