There's a lot of cracking up going on here.
Why would you baptize someone "at once" if they were in danger of death? That's easy. Why would one take any chances? If a thief broke into your house and you could confront him and win with a knife, why would you forego grabbing the gun that will give you the victory if you have at hand? That would be irresponsible and stupid.
Come on, Stubborn.
Or I guess we could keep laughing.
The RC tells you the reasons for not baptizing adults at once. I can tell you of a convert I knew who was baptized a Lutheran as a child, but upon hearing only the most basic of the basics of the faith, wanted to convert, and was desperate to be immediately baptized in the Catholic Church for fear of the previous baptism being invalid, sudden death and going to hell.
In my mind that was a valid concern, but the Church does not look at it that way. The Church ONLY looks at it that way if there really is the danger of death. When it comes to the baptism of adults, the way the Church looks at it is taught in the RC, i.e they are in need of instruction, among other things.
This is the key, this is what you are missing (I think)....
You have to believe that there is no one, not one single person in the whole history of the world, who being sincere in their intention and determination to receive Baptism and their repentance for past sins, which made them availed to grace and righteousness, that God will take before they get baptized.
It is with faith that we understand that Almighty God provided you and me and all who've ever been baptized with the time to do it, and the water for doing it, and the minister for doing it, which means simply, that if God arranged for you to be baptized, it is by the very same Providence He can arrange for anyone else who desires or is willing to receive it.
The whole problem with a BOD is that it only works when the Divine Providence is altogether removed from the formula.
If one can save themself by desiring the sacrament, then one can skip that idea and simply desire to ascend body and soul into heaven.