Meursault probably got the kim id because his behaviour is a facade to protect himself from memories he doesnt want to recall (memories of N corp paralleled with the memories of S corp). Probably
Not only is he intended to be a subversion of Hohenheim (sorta) hes also a statement on how "honour" in the city works. The most unbound person is the only one who can do anything "moral", but theyre also the one bound to make the most mistakes