It's not I explained myself poorly, you didn't grasp the fundamental concept which is different.
You always seemed to be Zoro biased so I will forgive you
If anything I don't see what I should explain about Zoro using CoO in order to spot the danger whereas it would not have been feasible differently. In fact he was capable to achieve something that would not have been possible had he not featured CoO. Clearly Zoro either tracked Daz Bonez or sensed his sword and that is how he managed to evade so proficiently in that circumstance, I would bet it was BoAT which is in fact a form of CoO, since swords are conceived as living beings in the manga.
You have no fundamental concept to grasp because your basis is nonsense, just a mess you can't even defend properly.
Unless Bonez put an intent behind the rubble falling (and I mean he pretty much made them fall exactly into those spots), observation wouldn't make Zoro know where they wouldn't fall, just like Enel couldn't predict Luffy's punches when he randomized them since observation doesn't allow you to spot the danger but an intent. Throughout the chapter Zoro shows us he isn't sensing any presence as he explicitly distinguished such concept from the breath he's hearing coming from objects around him, inanimate stuff that now seem to be alive as they're breathing —which is why Zoro knows where the rocks won't fall: not because he read Bonez's intent, which is what observation does, but because he could hear the rocks's breath itself directly from them.
Nobody is actively involved during this whole process; nobody is linking their alive presence to the tree, to the ground and so; nobody is putting any intent behind the things whose breath Zoro hears.
Zoro gets to slash Bonez not because of sensing his living presence but hearing the breath of the inanimate steel that constitutes his body. Equalling the breath of things to observation haki is so baseless that not even Oda made any effort to connect them when he cheapily retconned the former into armament haki with Hyogoro's speech; simply because, as I said, it was never conceived as haki but an idiosyncratic ability that was vaguely turned into, so far, busoshoku.
Zoro heard the breath of the palm tree and could not cut it. Zoro heard the breath of the steel and could cut it. No living, sentient presence there but objects breathing, not animate but inanimate things, and therefore no observation. Whether you fall for Oda's retconning and try your best to make any effort out of it is up to you (you've clearly been tricked by him since you're assuming that such performance required observation instead of considering that the breath of thigns was conceived as a different power), but the facts are that presence doesn't equal breath (explicit statement by Zoro), that rocks falling randomly can't be predicted with observation (just like Enel's situation) and that Zoro slashed Bonez thanks to hearing his steel's breath, not sensing his human presence.
