He speaks about it here...
https://plus.google.com/105237212888595777019/posts/UTKKo5Su6RjEssentially, legitimate companies never steal anything.
From the article above...
7. As image search and image recognition get better and better, there will be no need to watermark things. In 1 year+, we'll be able to r-click an image and choose "Google-find the original creator" -- there is a bit trail to first-on-the-internet.
8. Yes, last, there will be bottom-feeders that steal your stuff. I call this the cost of doing business on the internet. These are the Tic-Tacs that are stolen from the 7-11. It is impossible to maintain 100% of your digital inventory, so wanting "perfection" in your online strategy is an illusion.
The benefit of being seen everywhere outweighs losing some Tic Tacs.
Also - don't forget. It doesn't matter if you "allow" someone to download your photos from Google+, or any other site.
If I want, I can command+shift+4 and do a screen capture, and so can anyone else. So if you have a computer, you can grab anything that appears on your screen, regardless of "protection".