I understand what you are saying but it seems that the Catholic Church is making a definitive statement here. In other words, it looks as though the Catholic Church is saying that those who are not baptised can achieve salvation. Didn't Jesus say that one must be born of water (be baptized) to achieve salvation?
Well, the thief on the cross achieved salvation without being baptised in the name of the Father, the Son and the Holy Spirit. Catholic belief on Baptism includes the possibility that baptism can be-
* By Water and the Holy Spirit in the "normal way"
* Baptism of Blood. If for example a Catechumen of the Church is Martyred for the Faith prior to Baptism by water then the power of the Sacrament is imputed to them as if they had received it physically.
* Baptism of Desire. Those who desire Baptism explicitly or implicitly, or who would desire it if they knew about it, but are unable for some reason to be Baptized.
Also "invincible ignorance" is not considered to be a sin.
Cyril of Jerusalem said this-
"If any man does not receive baptism, he does not have salvation. The only exception is the martyrs, who even without water will receive the kingdom.
. . . For the Savior calls martyrdom a baptism, saying, ‘Can you drink the cup which I drink and be baptized with the baptism with which I am to be baptized [Mark 10:38]?’ Indeed, the martyrs too confess, by being made a spectacle to the world, both to angels and to men [1 Cor. 4:9]" (Catechetical Lectures 3:10 [A.D. 350]).
"[Besides the baptisms associated with Moses, John, and Jesus] I know also a fourth baptism, that by martyrdom and blood, by which also Christ himself was baptized. This one is far more august than the others, since it cannot be defiled by later sins" (Oration on the Holy Lights 39:17 [A.D. 381]).
"Do not be surprised that I call martyrdom a baptism, for here too the Spirit comes in great haste and there is the taking away of sins and a wonderful and marvelous cleansing of the soul, and just as those being baptized are washed in water, so too those being martyred are washed in their own blood" (Panegyric on St. Lucian 2 [A.D. 387]).
Ambrose of Milan
"But I hear you lamenting because he [the Emperor Valentinian] had not received the sacraments of baptism. Tell me, what else could we have, except the will to it, the asking for it? He too had just now this desire, and after he came into Italy it was begun, and a short time ago he signified that he wished to be baptized by me. Did he, then, not have the grace which he desired? Did he not have what he eagerly sought? Certainly, because he sought it, he received it. What else does it mean: ‘Whatever just man shall be overtaken by death, his soul shall be at rest [Wis. 4:7]’?" (Sympathy at the Death of Valentinian [A.D. 392]).
"I do not hesitate to put the Catholic catechumen, burning with divine love, before a baptized heretic. Even within the Catholic Church herself we put the good catechumen ahead of the wicked baptized person. . . . For Cornelius, even before his baptism, was filled up with the Holy Spirit [Acts 10:44—48], while Simon [Magus], even after his baptism, was puffed up with an unclean spirit [Acts 8:13—19]" (On Baptism, Against the Donatists 4:21:28 [A.D. 400]).
"That the place of baptism is sometimes supplied by suffering is supported by a substantial argument which the same blessed Cyprian draws from the circumstance of the thief, to whom, although not baptized, it was said, ‘Today you shall be with me in paradise’ [Luke 23:43]. Considering this over and over again, I find that not only suffering for the name of Christ can supply for that which is lacking by way of baptism, but even faith and conversion of heart [i.e., baptism of desire] if, perhaps, because of the circumstances of the time, recourse cannot be had to the celebration of the mystery of baptism" (ibid., 4:22:29).