I think the reason would be that when turning heelside, lo lean on the leg on that side (for me, turning right, as a goofy, means leaning on the right leg, which is in front, on a heelside) and on a toeside, you lean on the other leg (turning left, left leg, in the back), so that's why it feels natural to lean on on front leg on heelside and rear leg on toeside.
The other reason would be the one mentionned in my previous post.