Im sorry but this is just simply not true, at all. This has no basis in fact. Its more than likely the case that some do have an answer, and it is not well-liked. This is NOT an official Adventist teaching by any stretch.
Of course, this statement is made without any references or solid proof. The Bible is clear on this subject; and to be frank, its none of our business how God does things and "saves" people. Regardless of the age. He is able to save "to the uttermost," (Heb 7:25), and "His ways are past finding out." (Rom 11:33).
It is a matter of trusting God to do what we see no way of doing. There doesnt need to be a list, from a to b for everything when it comes to salvation. It is the cross - the shed blood of Christ that takes care of things we are completely inept at carrying out ourselves, and it is NOT ever up to us how God chooses to do that. No EGW needed. Unless you have specific references to prove what you are saying, sorry, I dont buy any of it. It seems like you are just on this forum to attack SDA beliefs. I dont buy any of it. It gets tiring reading all of the attack-mode dogma.
This "fulness" of God is recognized by babies and any others we can't figure out how God does it, byt the actions of those who are capable of knowing doctrine. Being present with them, in the spirit of love and acceptance is all the "light they need; and NO ONE has to have the "amount" of light that we say or think they should in order to be saved. As long as a person, any person, is alive there IS hope for them in Christ: "Ecc 9:4 For to him that is joined to all the living there is hope: for a living dog is better than a dead lion. " A lot of scripture has to be bruited into midnight hour gibberish in order to make it say that God cant save a child of parents who supposedly are "wicked."