to be honest having 30000 is not the big problem , Luffy using CoC haki should to take the majority of them , but BM and Kaido should be able to take Luffy's side as well or only those who are specialized in CoC are able to control their CoC to take people that way.
Doffy used it in PH but there were only a few soldiers. if that is how it is it would explain why neither WB neither Sengoku have used it in MF.