Does it use poo cubes to build things?
Edit:. A quick internet search suggests they poop in high up places to mark territory, and presumably the more typical round poop would fall off high up rocks and be a bad marker.
I've a wombat living on my property. The elevation we're talking about is only 20mm or so, in my experience. Most often it seems to be perched on an exposed tree root. I've heard it explained to me that they 'back up' to where they do it, so it's not as though they clamber up onto something.
That said, once I had a squared sawn log resting on an angle and it had wombat poo on it after a few nights and was about 300mm or so off the ground. The log would've been just manageable for a ground-hugging wombat to reverse up.
Wombats are territorial, and very regular in their nightly movements. The cubic poo may be in part a simple consequence of their body shape (squat, narrow, long - evolved to wiggle into tight holes leaving only their impenetrable back plate exposed to would-be predators through the day), or, as you observe, assisting in perching scat with less risk of it being moved.
As I understand it, the extra height allows for other animals to more easily detect (by smell, I'm guessing, but may be visual as well) their presence in the area - presumably with the intent that those other animals keep away.
I see what you did there.