EDIT: See my response to jedsmith below. I didn't look at the altered site when I posted the following:

Well, it doesn't look like the OP has actually done any vigilantism (at least not yet):

I simply altered the code of my site so that the next time his scraper tried to access its content, it wouldn’t get what it expected. Within an hour, the homepage and every page of his site looked like this (redacted to protect the guilty)

What he did can only target the guilty party, as all he did was change his own site's content.