I found this a bit hard to follow as what the author was saying and what he was responding to, but I think I understand what he is saying and really can't disagree. We must make it clear that good works are the fruit of salvation and not its root. We do good works (sanctification) because we are saved and the Spirit lives in us and don't do them to be saved. (Am I understanding this correctly as you explained it?)
We can do nothing to be saved as it is God's gift to us if we do not reject it. We can reject it in many ways over a period of time, not just by merely saying we reject it, but by our choices that direct away from the Spirit. That is why the Bible says that "grieving the Holy Spirit" is the only unforgivable sin.
I think truth is progressive and God reveals more and better ways to live to those who will listen as time goes on.
Who will be saved? Personal reflections from the Bible
Now when it comes to who will be saved, I know that those who heard Jesus speak were given a face-to-face chance for salvation and to believe in Him. They were lost if they rejected Him and what He said. Now He was talking to His audience at that time. The story of Jesus continues to be told (though sometimes distorted) ever since. Those who hear it have a choice.
Now this does not talk about the millions who lived before Christ was here on earth and the millions who have never heard of Him. How are they saved? All humans are saved by Christ (I believe) if they choose the ways of compassion and love because God/Jesus is love. There is a verse that says they see Him in nature and make choices.
The only way I can reconcile this is through the verses that say Christ died for all humans. Thus He reconciled them to Himself by His crucifixion. Therefore, I have to take the position that all are born reconciled and saved until they come to a point where they reject Him and His loving ways. There is a verse that says Christ was crucified from the foundation of the world. To God there is no barrier of time as there is for humans, so I believe He died for all of us regardless of when and where we live. I know that God is fair and just, and this is the only way I can make sense of salvation for those who never heard of Him.
However, you may say why do we need to spread the gospel and have missionaries? We need them because a majority of adults will make wrong choices and reject His kind of life unless the good news is brought to them. They live self-centered, sinful lives because it seems to come naturally, and they need to hear there is a better choice. Perhaps God winks at these times and places of ignorance, I don't know how He will judge, but He is the judge of all humanity, and I can only guess.
In the last days I believe the whole world will have a chance to hear the good news and a fair chance at salvation. This is possible through our growing use of information technology.
I know these are only partial answers I have come to in my personal study and there are some others who would agree with much of it, but we cannot have all the answers on this earth. One day we will be able to study them in the new earth. Right now, I trust Jesus.