Justification refers to being in a state of sanctifying grace, whereas salvation refers to entering the Kingdom of Heaven (the Beatific Vision). In this life, we can only be in a state of justification, and it then requires a distinct grace of final perseverance to transition into the state of salvation.
So we speak of the Old Testament "just", where they were in a state of sanctifying grace and yet were not yet saved and had not entered Heaven.
Now, the Dimonds argue that justification is impossible without the Sacrament of Baptism.
Fr. Feeney's position is that it's possible, but doesn't suffice for final salvation, and they make an analogy between this state and that of the OT just or justified. He did not believe, as a practical matter, that God would allow anyone who died justified not to be saved, that He somehow, even if in a manner unknown to us, made sure that all His elect received the Sacrament of Baptism and thus would be saved. When asked the hypothetical of, if this were possible, what would happen to such a soul, and he responded I don't know. I hold that they would enter a place like Limbo if they also died without any debt or stain of actual sin (as would be the case with an unbaptized martyr) or else in a Limbo-like state with lesser degrees of suffering that Hell proper. But that's a side point.
Given in that context, I suppose this is where I would place my position along with the Dimonds on justification. As the justification of the OT Patriarchs is wholly different than the justification Fr. Feeney proposes for the unbaptized after the Resurrection, as those under the Old Covenant were still able to attain justification by the merits of the OT sacrifices and rites which were made in the hope of the Redemption to come. So their sin offerings were accepted only insofar as they were united with Christ in the Redemptive Sacrifice of the Cross at the close of the Old Covenant.
This is not possible for the unbaptized because after the establishment of the Church and Sacraments, post-Resurrection, the only means of justification would be by those same Sacraments. They are the only way to be justified, as there is no other way that the unbaptized can receive the remission of actual sins without the laver of regeneration. And we all know that without God's grace, it is impossible for adults to be free from actual sin, so even if they died with a single sin on their soul they would still merit hellfire. Unlike unbaptized infants who cannot commit actual sin, and therefore lose the Beatific Vision, but do not merit hellfire.
So to say they would go to a Limbo not unlike that of the infants, is extremely unlikely.