I personally am quite confident he will see full colors.
As many color blinds can anyways see colors with some special corrective glasses.
And they then immediately recognize/see colors, that they have never seen before without problems. So it seems to me, the basic color identification is very deeply rooted in the brain, and works immediately even for people not being able to see these colors before.
BTW: These correction glasses work by filtering a certain range of wavelengths.
Color Blinds usually have the problem that usually two of their color receptors have a too similar wavelengths response, basically always activating both at once or none.
The glasses then block any wavelength these cones share, like that this double activation for a single wavelength cannot happen anymore.
The inventor of the glasses got aware of this effect, while working in the laser lab, as there you have glasses blocking a certain wavelength. He as a color blind suddenly saw different colors, and asked himself, why.
There are certainly also other causes for color blindness, but AFAIK this type is the most common.
But again this is surely just a guess. And I take no responsibility for the correctness of my explanation...
I claim not that this is the truth. As this is just what got manifested into my mind at the current position in time on this physical plane. So please feel not offended by anything I say.