He would be free to not ask Mary or the Saints to pray for him as that is just a benefit to the faith, not the center of our faith.
Our worship is centered on Jesus, if perhaps a hymn or a prayer includes asking the intercession of Saints he would not be forced to do this and would not be excommunicated. Most everyone would not notice anyways as our worship is focused only on Jesus.
Yet he cannot deny that the Saints are in heaven, alive in Jesus, love us and are part of the Body of Christ. If we ask for their prayers that is more personal.
He would have to accept the belief in the full Body of Christ, yet would not be obligated to participate in the parts that he is not comfortable with.
I do not sing some songs that they sing in Church as they are kinda heretical, I focus on remaining true to Jesus and not misrepresenting my beliefs by following along the songs of some wacky choir person.
As a Catholic my center of faith is Jesus and a fidelity to the truth He expressed. So I am perfectly free to affirm that quietly and honestly. That is also why I gravitate toward the priest to recieve communion, instead of some guy\lady in a robe.
In Christ,
Scylla
(as someone else said, whether you know it or not they are still praying for you as Saints in heaven are all worshipping God and we join them at Mass)