the problem is the vague language. “as he conceives them” — due to what? due to the direction of God (that’s great) or due to some unknown factor (that’s asking for big trouble)?
As other have noted (and I have noted, as well), part of the problem is translation. The thread linked twice in this thread has a discussion by Fr. Zuhlsdorf, an American priest currently residing in Rome, who is pretty fluent in Italian.
In the case of “conceives,” Fr. Z believes that's not such a good translation, but rather, what is being said is more along of the lines of becoming aware [of the objective moral law]. Which is actually Catholic teaching, that men are capable of becoming aware of, of learning, of detecting, of developing a conception of the moral law unaided by grace.