User blog comment:18emerc/Superboy and his abilites/@comment-50.14.65.44-20130223013850/@comment-432124-20130225015254

The point was not whether he got over it; it was whether or not Superboy's allies attempted and were able to fix his aging condition, which they obviously did not succeed in. And if they, with all of their resources, weren't able to find a cure, they likely wouldn't have been able to find any unknown side effects caused by his genetics.

Also, from what I read in the comics, Superman's DNA did not heal him from Doomsday's attack. He had to be put in a healing chamber in the Fortress of Solitude so that that would resurrect him. And even that wouldn't have happened if Nekron didn't want him as a sleeper agent for his Blackest Night. That being said, considering how much less powerful Superboy is than Superman, his partially Kryptonian DNA wouldn't be enough to fix this kind of problem