A lot of people are also assuming that these guys are "Americans" and that people will "recognize" them. They could be illegal aliens. And maybe they are not even in America now!
As for finding those cards, man, that's gonna' be tough. Sure, a few are rare, like that WWG DiMaggio, Caramel Ruth, Sporting News Jacksons, etc. However, all the others are not. For example, up here in Canada, there are hundreds of people who own that 52T Mantle. I know that for a fact. They're always turning up here and there. Now, imagine how many there are in the US?
And as for the other cards, there are probably thousands of them in the US. These guys could sit on them for about a year and then just slowly put them back into the marketplace. I know they're graded, but they can get cracked out and the raw cards can get worked on a little bit in order to prevent anyone from matching them with older scans. And even if they don't work on them, I doubt that a year from now anyone is gonna' be doing checks on their newly-purchased cards. People are just gonna' be so absorbed in their own problems and will totally forget about all this.