I don't disagree with this comment. The scare quotes is because the AI wouldn't literally be editing the C++ (or whatever) code directly, the sort of things that a reader might think of when I say "editing source code." Rather it will probably manipulate encodings of thinking processes in some sort of easy to analyze recombinant programming language, as well as adjust weighting vectors as you mention. There's a reason LISP, where code is data and data is code is the traditional or stereotypical language of artificial intelligence, although personally I think a more strongly typed concatenative language would be a better choice. Such a language is what the AI would use to represent its own thinking processes, and what it would manipulate to "edit its own source code."