Yes, it's a public photo. But seeing all tagged public photos in one place is a different thing. These photos are not shown when you click "Photos" on his Timeline: https://www.facebook.com/zuck/photos_all
That's interesting. For your friends, there is a "Photos of <friend>" item on their photos page, but for non-friends it doesn't show.
But OTOH, if you're tagged in a public photo, like this case, I'm not sure what expectation of privacy you should have. You can trivially untag yourself.
I just played with the graph search and that thing is creepy and powerful. It pains me that I'm drawn to such tools and I definitely need to stay away from that one.
Yes, it's a public photo. But seeing all tagged public photos in one place is a different thing. These photos are not shown when you click "Photos" on his Timeline: https://www.facebook.com/zuck/photos_all