Leprichan
Sapling
Make sure you keep up with the thread Sorce linked to. It has continued to update and addressed those roots, as well as the idea to cram a rock into pre-existing exposed roots. The advice on where to cut is exactly applicable to your tree.
The short story is this: keeping those stilts is a bad move in the long run, and any effort and time that goes into growing roots below them will end up wasted when you eventually decide to cut them off.
I have, was actually plotting were to chop the roots in the future this morning. Right now I'm trying multiple different things trying to really learn this type of plant, I'm gonna chop the roots of this trees sister plant( from same pot when bought) later this year in anticipation of chopping this trees roots. The rock isn't a permanent thing, being the root chop will be above it.