He is using the body of zetsu after all, that's why the hokages didn't get caught in IT because they are zetsus (Obito too... sort of) or because they're dead... sort of.
The purpose of IT is to turn humans into zetsus, but Oro is already one. Him getting caught seems redundant.
The purpose of IT is to turn humans into zetsus, but Oro is already one. Him getting caught seems redundant.