I have read the Latin, and the original Latin could just as easily be read as,
their proper dispositions would avail them to justification were any sudden obstacle to arise that might [otherwise] prevent them from receiving the Sacrament of Baptism.
It's a nuanced "subjunctive" mood (a grammatical construct) that indicates hypothetical, something which we do not have in English. In other words, their dispositions would get them past anything that might otherwise prevent them from receiving the Sacrament of Baptism. It's along the lines of the St. Ambrose oration to Valentinian.
St. Fulgenius used the exact same phrase. He said that a catechumen's "confession" (embracing the faith) would avail him to righteousness. But if you look about a sentence later he says that it's because God would make sure that such a one would receive the waters of Baptism. St. Fulgentius' texts regarding EENS were well known and were paraphrased and quoted by some of the dogmatic definitions.
Agreed, yet having the proper disposition is the preparation, a necessary function one needs before one actually receives the sacrament if one wants to receive the sacrament as worthily as possible, that is what the word "avail" is dictating.
It does not say that having the proper disposition will grant them salvation if the die before getting baptized, which is what the BODers insist it is saying.
Either way, the catechism teaching in question states some of the actual reasons why the delay is, preferable, even advantageous for the adult catechumen - - - which is why I asked the NSAAers to list those what those advantages to delaying adult baptism are which the catechism teaches. It's not like it's my teaching, it is taught in the catechism, right there big as day.
It is no trick question, the reasons are given right there, all they need to do is copy and paste, yet they insist the reason the danger is not the same in adults as it is for infants because the catechism simply *must* mean the adult wins a BOD if he dies without the sacrament.