Ctrl+C means copy the text, with optional formatting. It doesn't mean "run a script", and this little trick implies two things: first, that the author is going to assume that anyone who copies text is trying to steal the content without attribution; secondly, that having been corrected in your naughty ways, you'll blithely accept the link he's pasted in there.

It's a web faux-pas, the equivalent of having your whole site in Flash, or trying to disable right-click for fear that someone might steal your precious, precious content.