The Catholic Catechism disagrees with you:
2358 The number of men and women who have deep-seated homosexual tendencies is not negligible. They do not choose their homosexual condition; for most of them it is a trial. They must be accepted with respect, compassion, and sensitivity.
And, in 2357, the Catechism says "Its (homosexuality) psychological genesis remains largely unexplained."
Possibly environment, but possibly genetic as well.
They must be accepted with respect, compassion, and sensitivity.
This is very true, but the Cardinal's point is do they belong in the Church as priests?