" Does this make the unbaptized deliberately deprived of grace?"
No one is "deprived of grace". Some may not respond to it, intentionally or otherwise, but God's grace falls on the good and the evil, the baptised and the unbaptised equally, or so the Fathers taught.
We teach the same: "For God on His part is ready to give grace to all men: He wills all men to be saved and to come to the knowledge of the truth (1 Tim. ii, 4). But they alone are deprived of grace, who in themselves raise an obstacle to grace. So when the sun lights up the world, any evil that comes to a man who shuts his eyes is counted his own fault, although he could not see unless the sunlight first came in upon him." (St. Thomas, Summa Contra Gentiles, III, 160).
Actual graces, yes. These are the holy inspirations which direct our thoughts and works to acts of piety.
Sanctifying graces no. Sanctifying graces are communicated in the main through the Sacraments, Sacramentals, and prayer.
An atheist does not have sanctifying grace "rain down upon him". He does receive actual graces prompting him to faith, if only he would cooperate with them, and if he had faith, he could then receive sanctification.
To say that sanctifying grace rains down on all is to make it only effective upon our cooperation with it, rather than of itself. It is inconceivable to us to think of the Holy Spirit dwelling in a sinner, and he only failing to obtain the good benefits of God's grace due to his own obstinance. Just as the Glory of God left the Temple at its fall (Ezekiel 10.18), so the Holy Spirit leaves the soul of the sinner at the moment of sin.
Basically, you seem to be saying that God is already all in all, and that a man needs nothing but self-actualization to realize that God is already within him. This sounds very New Agey.