His objection may be somewhat understandable given the fact that he, like many, don't understand the implications of believing that upon her death Mary was immediately taken body and soul into the glory of eternal life.
The Church presents Mary, in her sinlessness (Immaculate Conception) and in her death (Assumption)as a model for God's promise to all of humanity, a promise not just of a spiritual eternity with God, but one which holds out the promise of a bodily resurrection, in the fullness of time, for all of us.
So, why is this significant? In a world which is seeing so much violence, killing and suffering God's promise is that this will be overcome, that bodies are not just cast off so that we can live some sort of ethereal life in eternity. The implications of this belief, however, extend not only to our time after death, but to this life as well. One of the great errors present in Christian history is the dismissal of the body. We forget that the Word became flesh. As a result of this we have tended to have a skewed understanding of sexuality, continually bouncing from hedonism to puritanism. We talk of saving our souls forgetting that not only the body but the entire created order is the subject of the redemption that Jesus brings.
This is why we care for the sick, why we respect the whole human person, body and soul. It is why we stand against racism which says that the color of some bodies makes them superior to others.
It is interesting to note as well that in the Gospel for the Feast Luke has Mary proclaiming the beautiful prayer, the Magnificat ( See the image above). After she thanks God for what has been done to her. She proclaims that the hungry will be fed and the lowly will be raised up.
An interesting historical fact. When Pius XII declared this belief as a dogma in 1950 he did so with the horrible suffering of two world wars and the holocaust in mind, top hold out hope for humanity.
If that message is not relevant for today, what is?
PS. It was on this day in 1964 that I took my first vows as a Franciscan