The second quote is legitimate and makes a very important point, that is illustrated for instance by people who voted for Nader because Kerry wasn't leftist enough for them, increasing the chances of Bush, their least favorite choice. Nader was a poor choice for them because his election was impossible -- the point of the quote, that perfection isn't reachable.
As for the first quote, it would be better expressed as "the adequate is the enemy of the excellent".
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