I do not know how well I have understood what my son reported, or how well my son's report matches the teacher’s actual instruction, so I will only respond to what I understood from my son's report. Whether or not it accurately reflects the teacher's position, it is a real position out there in the Christian world, so it is worth discussing.
This sounds to me like a version of particularized prevenient grace, kind of a best of both worlds or a compromise approach. The Semi-Pelagian doctrine of prevenient grace says that the Fall incapacitates everyone's ability to choose salvation. But God gives to everyone a grace that fixes that incapacity. Now that that problem has been removed, people can use their free will to choose salvation. Or not. Some may choose salvation but others refuse to take advantage of the grace provided and remain eternally lost.
This differs from a Reformed view which says that every one is incapacitated, and God gives saving grace to particular people according to his sovereign choice, enabling them--dare I say even causing them--to turn to Christ. None except those who have been enabled by Christ will turn to Christ because "no one can come to me unless it is granted him by the Father” (Jn. 6:65). Additionally, no one who is enabled ultimately refuses Christ, but instead "all the Father gives to me shall come to me" (Jn. 6:37).
What I understood my son to be reporting was that the work of the Holy Spirit, though it may be given only to particular people, simply returns people to either a neutral or repristinated state (the original condition before the Fall), from which they then make a free will choice for Christ. Whatever happens to us in this process at least removes whatever was keeping us from turning to Christ, and so we choose Christ of our own accord.
This smells of a frequent problem in theology. We affirm all the right things up until the hard points, and then we cave. For some reason (anyone want to guess?) human beings are compelled to preserve some right of place and position for free will in the salvation process. The bogey of free will is the darling of Arminianism that always seeks to find its nook and cranny in everyone's theology. And it will continue to do so unless and until the theologues are willing to say God is the absolute, supreme, sovereign creator, and we are only as free and as limited as God wants us to be.
Whatever free will may be, it cannot hold God's sovereignty hostage to man's will. If it did, God would not be God. Free will is a tough subject, and even Reformed theologians disagree on how to work it into their theology. They do not tend to deny it at least. But what is common among the Reformed is to affirm that at no point does man's free will have any capacity to frustrate the will of God. However one defines or uses free will in one's theology, it is important to do so in a way that does not have that familiar idolatrous air that encroaches too boldly upon God’s sovereign free will to do his good pleasure, even with the souls of men. Free will that must exist in a system simply for free will’s sake is idolatrous. For man to maintain the proper place for free will in his theology, he must first be willing to give it up completely to God’s sovereignty. I suspect that if a person were truly willing to sacrifice it, God would reveal its proper place over in the bushes.
Now back to the classroom—
Remember that the will of man before the Fall may have been sinless, but it was not immutable (unchangeable). It was in fact very mutable (changeable), as evidenced by the fact of the Fall. So to return someone to the original condition in the garden would have only returned them to a mutable state, which is hardly a position that requires that they come to Christ. If they are returned to an original state, then they would only return to the original state from which Adam and Eve rejected God in the first place.
And remember that Adam and Eve had the advantage of pristine goodness. No Christian has that, because no Christian will be rid of his remaining sin until glory. How does bringing someone to a mutable state of imperfection fix the problem that inevitably comes from throwing the salvation-decision back to man’s disadvantaged free will? It would not create a necessary choice of salvation, would it? It still allows room for free will to frustrate the plan of God regarding a person’s salvation, right? Unfortunately, remaining sin causes Christians to turn against Christ's will all the time, at least for a time. How is this partial, mutable, and imperfect repristinization sufficient to—in this moment only--guarantee a free will choice of Christ’s will and way?
So God’s returning someone to an imperfect mutable condition from which to make a free will choice does not reflect the force that Christ expresses when he says, without equivocation, that “All that the Father gives to me will come to me.”
It sounds to me like the work of God goes much farther than simply wiping the slate semi-clean so that a man can try again and get it right this time. Or get it wrong again. It’s his choice after all. Right Adam?
BTW, I am very happy that my son is being asked to continue to think through these things after he has left the home. I am grateful to the professor for providing the diving board and pool for lots of fantastic, theological and philosophical exercise. I am sure he brings up a lot of ideas and suggestions for discussion that he either does not agree with or cannot fully elaborate on. Looking forward to many more great discussions with my son.