I believe Xavier is referring to the position of the SBC as being that God will provide the sacrament
to all of His elect, to all the saved. I think that indeed is the SBC position. I believe the SBC recognizes that someone could be justified by desire and if they died before receipt of the sacrament in that justified state they would be saved, BUT THAT'S A HYPOTHETICAL AND NEVER HAPPENS.
Thus, the SBC agrees with the Roman Catechism that "should any unforeseen accident make it impossible for adults to be washed in the salutary waters, their intention and determination to receive Baptism and their repentance for past sins, will avail them to grace and righteousness." The SBC then adds, "but there ain't no should."
Xavier says this is the position of St. Augustine (we can at least say he joins St. Thomas in citing St. Augustine as recognizing BOD), and Xavier then closes as to the position of St. Augustine/the SBC: "St. Augustine's view is excellent, very probably true, and eminently defensible."
Good for him.