Idk, Oda doesnt kill off Shichibukai's from what we saw but Moriah dancing on BB's tunes sounds weird as well...
I hope Moria gets the last hit on Kaido, that would be epic. It doesn't have to be Zoro. Zoro will wear him down.
He may not have a real choice on the matter. However he will surely plot against BB and betray him later.