If they want to provide deep linking to a particular map location they should change the URL without writing to the history.
You've been presented with these rare images, that someone probably had to smuggle out of the country, took care to lay them on the map for your convenience, and you sit there dissatisfied with how the back button works.
Just for fun: https://hn.algolia.com/?query=%22my%20eyes%20hurt%22&sort=by...
I can't help but be curious if it's falling back to #hashurls for you (or something else). From my end, they've come up with a clever technique for persisting map state in a sharable way.