I believe that it is the Will of God that all men be saved, and I also believe that God knows when a person is most likely going to cooperate with His good grace.
He gives to some at the last moment a flood of grace, and maybe that is what happened to your brother. Sometime it is just a thought like, God have mercy on my soul, that will save you at least from Hell.
It is those who presume to have this special grace at the moment of death that will be denied. Those who do not presume, and especially if someone is praying for them will be given another chance. Perfect Act of Contrition it is called. None of us really know for sure how God works in the souls of people, which is why we can not judge the soul of a person who dies.
Although many people do judge, I feel sorry for them, because they will be judged harshly as they judge. Unless of course they repent of such judging.
Gods mercy is greater than any sin, for to say that sin is greater than God's mercy is heresy. Not to say that all men are saved, Hell is so full of souls that sometime I think, if Hell is really in the center of earth, this oil spill is Hell vomiting.