Yesterday, Google equated their new site scraping technology with a swiss army knife. Because obviously swiss army knifes are helpful and site scrappers aren't. Great spin and all, but the fact remains that web masters are starting to see more and more of their content stolen by Google. I personally wouldn't mind this new feature if Google offered an "opt out" in Webmaster Tools, but I doubt that will happen anytime soon.
So, if we can't opt out of knowledge graph, then maybe theres something else we can do.... I used to have a blog that got scraped all the time. To stop the scrapping I would embed a large obnoxious image into the first paragraph that basically said that the blog post had been stolen. Then I would hide the image with CSS. That way the image remained out of sight on my blog, but would be visable on other sites if the content was scraped, because the CSS would remain on my domain. It is a fun trick to catch scrapers red handed.
However, Google is way smarter than that. They are removing any embedded HTML on the fly. Which means you wouldn't be able to hide an image. BUT, what if we could hide some text? Or better yet, just edit the text to provide false information? Take a look at the fun that some are already having with this strategy. :)
Ok so hiding text? How would that work? This is purely hypothetical, and to be quite honest I am not advising anyone to do this, but.... Lets use this result with moz.com as an example:
What if somewhere in the text above you embedded something like <span style="display:none">This text is being stolen by Google with out Moz.com's permission.</span> The inline styles will hide the text as long as it is on Moz.com, and presumely the text would appear on Google.com if they are in fact deleting embedded HTML while scraping.
This could be a lot of fun, however, I have no idea if this violates any of Google's TOS, or guideilnes, as such I would never advise you or a client to attempt it. But as long as Google refuses to give an opt out option for these types of results, then I think we are justified in treating them like any other scraper.