1) Didn't anyone, in the entire time that Solidus was President, comment on how Solid Snake looks like the President of the United Fucking States? Or comment on how Solidus looks like Big Boss?
Snake is a legend among boorish military types, but how many people had met him face-to-face at the start of Shadow Moses? The only people who would recognize him are his old FOXHOUND crew, and most of them are dead (including
Miller). Meryl might have noticed, but they were in the middle of a mission and too busy fighting for their lives. Campbell might have noticed, but he wasn't in a position to do anything about it either.
Besides, going by the illustration we see during Raiden's face-to-face with the President, Solidus looked very plain as George Sears:
Gray hair, middle-aged. There's probably a million men in the US who look at least a little bit like this, and Snake looked younger, had brown hair and was wearing a bandana. I'm not surprised Meryl didn't notice.
For all we know, Otacon probably did bring it up during their down time in Philanthropy.
O: Hey, you look just like the last President. You ever notice that?
S: *grumbles*
And that was probably the end of it. Who else would have noticed between Solidus' presidency and his death in the Big Shell Incident?