Implementing a context based downranking policy on the results when they use a search engine (Bing) over which they probably have almost 0 ability to tweak or fine tune before the query sounds like an incredibly hard thing to do. You'd have to do a lot of contextual analysis and understand not only the query but also all the results the API gives you,
after the search is already done. That seems even more complicated than just having your own search algorithms at that point.
It's possible but it's hard to believe they'd go through that effort and coincidentally come up with something very similar to what Bing started doing too. I don't want to assume they are lying but this can very well be just an attempt at free PR when the truth could be just that it wasn't their decision at all. ddg does not seem to be very upfront over their almost total reliance on Bing in the first place.
I mean IIRC when the tank man picture disappeared from bing and thus from DDG too, duckduckgo acknowledged the problem but it didn't seem like they could do anything about it but wait until Bing fixes the issue.