The reason for the concealment is looking at this from a prisoner's point of view not a tourist's. They'll take away your pocket knife in a snip, but they might not notice the scalpel blade in your wallet. Its similar to the idea of a PSK except you have the added challenge not just of losing or breaking your primary gear but of having someone actively attempting to take it from you.

Plus you're looking at this from an American point of view where you have civil liberties and the LEO's predominately have common sense. In the US, a pocket knife needs little to no explaination, in another country its grounds for summary arrest. Doesn't matter whether you were concealling it from a search or not.