BOAT is a "mix"of CoA definition and CoO.
People talking about Zoro "sensing" >>>stones<<< and, therefore, using CoO.
But CoO (and Mantra) is said to be the ability to sense living things.
Imagine if you can just use CoO to sense where the road poneglyph is. :P
There are probably times when people use CoO use it to sense inanimate things, but, as I said before, CoO is the most inconsistent of the 3 types.
There's 0 sense saying anything else but Mantra or actual CoO usage (like the snake sisters) is, indeed, CoO.
Trying to make sense of something that, to this day, the creator himself can't actually explain properly is a fool's errand.