I cant read their mind, but maybe it takes account of the fact that some with disfigurements may come back without them. So they will be a new improved version of what they where. So not exactly the same but similar enough for you to know that they were still them.
The whole concept has very little detail. Do they come back old and disabled or do they come back looking like they di when they were 30? Do they come back with Cancer and then it disappears slowly. Do they come back with only one leg and the other one returns in time. Are disabilities and diseases on a sliding sale where some they come back with and some they don't?
That is supposing the whole thing wasn't a load of rubbish to start with. And even if it was true they would not be coming back anyway it would just be a copy of them.
The point is even though they have made the theory up they don't really know what it means and just make wild guesses while telling the rank and file not to speculate.