he is not wrong.. its not necessarily true.
you can debate the likeliness tho you can say it is more likely that he has it.
its not as simple as if "a" has it then "b" does too
but what basis? you have to have basis how does zoro having it proves that Mihawk has it? that why you should debate the likelihood not the certainty
tbh this the same route sanji fan use to prove sanji's Coc.. i'd call it Contingent variable argument (one has it the other must as well but the basis are just vague or veracious similarities that prove the likeliness than prove the certainty)
Hope you get it.