I like the slanted design where appropriate.
I had an opportunity just recently to work with a lady hobbiest who had a nice shore pine. It was planted in a square masculine pot and upright dispite it's mound of roots off to one side. I propped it up with a tilt of about 30 some degrees to the right and stuck a nice drum pot in front of it where the base of the tree began a bit left of center.
Made my day to see the smile on her face.
Time spent in the forrest, saw how easy it was to justify the slant because of the one sided root structure, which seemed to want to grasp the earth as a counter balance to the way the tree was leaning. totally natural looking and believeable in design.
In your case, (again back to the woods) I could see a stone to the left of the tree (where her root ball was on the pine) as if to suggest the seed landed there from the wind, and the young shoot leaned out and away from the stone to get it's needed light. As it lengthened I'd be training it back toward the stone as if the tree was making an effort to climb higher towards the sun.....in a more direct trac once clear of the stone.
Just some thoughts on how I envision things with my own subjects....maybe not for you
But perhaps to some, a different way of looking at things.....