But how can you attack something that is deemed at the least "proximate to the Faith" by several theologians and de Fide by some others as if it were heretical? This is the real issue - even if it is not dogma, it is by no means heretical, and those who agree with Fr.Feeney sometimes seem to treat it as such.
Baptism of desire is not a sacrament, but it produces the fruits of the sacrament, which include the transition to new birth, as Trent says, and therefore necessarily incorporation into the Church. Just like with penance and perfect contrition, the virtue is not considered apart from the sacrament, but nonetheless immediately effects reconciliation.
It is not possible to argue that a man who thus receives the new birth and sanctifying grace still remains strictly outside the Church, for there is no such grace given outside her. He is mystically united to the soul of the Church, the Holy Spirit, and is consequently on the way to salvation.
Nor is it reasonable to say that a man who dies in the state of grace is lost, because this is impossible. He who dies in the state of grace is saved as surely as he who dies without it is lost.
What is legitimate to believe, although one cannot condemn the opposite opinion, is that to all wayfarers who do receive such saving grace during their lives, the visible ark of salvation will eventually, through the ways of Providence, make her way, so that they may visibly enter it.
Also, a just consideration will show that we can have, as we are taught, no "good hope" for the salvation of non-Catholics, even if they do receive grace, for as any Catholic can testify, there remain abundant opportunities in this fallen world to lose that grace, as Pope Pius XII also taught, there are superabundant helps that can be had only in the visible body. And is it seriously to be hoped that a man can truly love a God of whom He knows but little, or who is presented in such a false sense as in other religions? And if he does, then he will receive the good news that God sent His Son into the world to die for his sins, with gladness.