That project seems to use some other kind of API. It does not handle real octree/3d data AFAIK. I've only seen quadtree and terrain elevation stuff there.
I've never before seen "fair use" called out as an explicit allowance in terms of copyright restrictions by the part of the copyright holder. It's not entirely clear to me what that would even imply.
I suspect they're trying to give more reassurance to "personal, non-commercial use is allowed as long as you don't hit our servers too hard" --- which seems to be their stance on a lot of their other services too.