This is a miscommunication, you two are not really in disagreement as far as I can see.
If someone {presents as an effeminate man} AND {they say they’re non-binary} => {they are non-binary}.
However if someone {presents as an effeminate man} AND does NOT {say they’re non-binary}… Then it’s not sufficient.
Whose authority says it’s not sufficient? If they say they are nonbinary, they are nonbinary.
This is a miscommunication, you two are not really in disagreement as far as I can see. If someone {presents as an effeminate man} AND {they say they’re non-binary} => {they are non-binary}. However if someone {presents as an effeminate man} AND does NOT {say they’re non-binary}… Then it’s not sufficient.