Because it’s not a matter of his beliefs. He claims he believes what the Church believes.
The problem is his actions. He has acted to keep abortion legal and to make embryo-killing legal etc.
Don’t you see a difference?
Here is why I think the church should not single out one person for what others may do.
I used to belong to the Greek Ortho. Church. I had seen so many marriages fall apart. Many failed due to extra-marital affairs with people in this same church. Now why is the church marrying people who have done this but the Catholic Church tells someone like Kennedy, no, you cannot take communion?
I guess I just look at it differently. Also, so many in the church I belonged to were very pro-choice and while I do not know if any have had abortions (I really do not want to know), they and the adulterers continue to line up for communion.
I know we are not perfect but this seems hypocritical to me.