The meteor is not bigger than chibaku tensei, it was smaller than Madara's perfect susanoo which is smaller than a mountain. Chibaku tensei made mountains look small.
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The best chance perfect susanoo has at destroying chibaku tensei would be to destroy the core immediately, the core picks up rocks fairly quickly so he wouldn't have much time and can Madara pull it off whilst being dragged into the core? The core also isn't that fragile even though it was still forming it took a tbb, rasenshuriken and Itachi's susanoo attack to destroy it so a single slash may not be enough.
Why comparing Chibaku Tenseis final stage with its initial? In its final stage not even the combined attacks of the Jinchuriki and Itachi would have destroyed it. But if Susanoo swings its sword, the attack will hit Chibaku Tensei when it will be mountain-sized. If we consider that a mere swing destroys a meteorite and cuts a distant mountain range, consider what Susanoo would do when using its second sword and going on rampage.