By your logic women are not an acceptable image of God on earth.
He sees Adam and Eve as both in the image of God.
And he would agree with Jesus as the new Adam, based on the various texts. Through His obedience He brought life to all men in Him, whereas Adam, through his disobedience, brought death to all men in him.
Where I think you are talking past each other is that he is noting Adam and Eve as being one flesh, joined together by God as husband and wife, given the command to be fruitful and multiply, and that Eve was mother of all the living. And the one flesh, husband and wife relationship would not be present in Jesus and Mary's relationship.
You might need to clarify that the new Adam/New Eve relationship either
a. does not include that
b. includes that in some very different way.
Beyond that, the Mary being the new Eve argument is that Mary was obedient, and through that obedience, participated in God's plan to bring salvation.
But it goes beyond that in that it claims sinlessness for Mary, which he does not accept. Mary, in the new Eve view, is seen as an archetype of obedient humanity, to the extent of being without sin.
And the conversation is complicated by different hermeneutics. The first step to any agreement would have to be to look at whether the texts present in Scripture rule out Mary's sinlessness, or not. Because a hermeneutic that values tradition, seeing Scripture as part of that, should still not contradict Scripture.