It doesn’t. The list is for the readers, the laity. the Catechism is for the laity, not the clergy.
It gives references. It states that they consulted the Bible, and where they did so.
I just post it to illustrate that the Bible is certainly regarded in this situation, and that in at least this religion, does not rely on Leviticus.
If so, I’m glad. I don’t get any particular jollies in giving any segment of Christian practice a worse rap than it deserves.
What I might be most concerned about is that the Roman Catholic church might believe the best a former homosexual could do would be to attain to a virtuous singlehood (if that is what is meant by chastity). Evangelical practice, at least, has sometimes seen better. Please don’t put a lid on what God can do.