We do index many things (see related comment at https://news.ycombinator.com/item?id=32360874). We do not remove any results ourselves for political purposes and in fact we have been banned in China for many years for that very reason. What you're referring to was a temporary bug in our image search results from Bing that they promptly fixed. If they hadn't fixed it promptly then we would have taken further action.
Just now I went to RT.com and searched various article titles verbatim on DDG, they came up near the bottom half of results. I repeated this test with WSJ and found the link as the #1 result. From this it wouldn't be unreasonable to believe that either you or the sources you pull from are engaging in arbitrary website throttling/downranking.
I hear you when you say you don't remove content, but do you, or to what extent do you throttle/downrank websites?
You don't index shit yourselves so when Bing censors something you do too.
[0] https://news.ycombinator.com/item?id=27394925