You are being completely unrealistic. Just the natural aging of the body will not allow him to look as good at 51 as he did at 35. I don't care how great his genetics are, it ain't gonna happen.
I think about someone like Dennis Newman after his return. Now very different circumstances considering Dennis' health situation after several years of layoff and then to come back and not look close to where he was.
Or take Victor Martinez after his layoff due to jail. Came back, blew up, but no where the quality as before.
Is Levrone genetically superior to Vic and Newman? I would say so. He's healthier to boot. Of all the 90s bbs the ones I would pick to have success in a legit, quality comeback would be Levrone and Wheeler.