I guess I don't see the problem with calling your shot an ace and why the rule wording needs to be changed. The only way your shot wouldn't have been an ace is if the group saw your shot get to that position from a skip shot coming into the basket from under it. Because we allow baskets sunk in the ground (like your example here) and nestled in trees, we'll have scenarios where another surface like the ground or a tree trunk may also be providing some support. Note that if the disc is wedged on the outside of the basket up against a tree trunk, the shot wouldn't be holed out because it wasn't touching the inner side of the cylinder.
Rater of the tossed arc.