CathInfo.com

St Alphonsus is perfectly in line with Trent. BoD is not a sacrament but just analogically so as it lacks matter and form. If St Alphonsus was in error in his teaching on BoD, he would have been condemned but instead was canonised by Gregory XVI and later proclaimed doctor of the Church by Pius IX.

Baptism of desire is perfect conversion to God by contrition or love of God above all things accompanied by an explicit or implicit desire for true baptism of water, the place of which it takes as to the remission of guilt, but not as to the impression of the [baptismal] character or as to the removal of all debt of punishment.

For, in those who are born again, there is nothing that God hates; because, there is no condemnation to those who are truly buried together with Christ by baptism into death; who walk not according to the flesh, but, putting off the old man, and putting on the new who is created according to God, are made innocent, immaculate, pure, guiltless, and beloved of God, heirs indeed of God, but joint heirs with Christ; in such a manner that absolutely nothing may delay them from entry into heaven

But though He died for all, yet all do not receive the benefit of His death, but those only to whom the merit of His passion is communicated; because as truly as men would not be born unjust, if they were not born through propagation of the seed of Adam, since by that propagation they contract through him, when they are conceived, injustice as their own, so unless they were born again in Christ they would never be justified, since by that new birth through the merit of His passion the grace by which they become just is bestowed upon them.”

Now ... a strictly limited BoD such as what St. Robert held, would not create fatal damage to Catholic ecclesiology, where it's only possible for Catechumens and those who are practically such, with explicit faith in the Holy Trinity and Incarnation, and intending to become Catholic (even if their status had not been formalized).

But the SECOND you extend BoD to anyone else, to infidels, for instance, or to heretics (and it's laughable, and exposes their motivation when some apply BoD to even baptized Protestants), but once you extend the possibility of salvation to non-Catholics ... YOU HAVEN'T GOT A LEG TO STAND ON IN OPPOSING VATICAN II.