So does it? Or is it safe only because NSA hasn't bothered to go to DDG yet, or do whatever they are doing to get Google's search data (cable splitters or whatever)?
Yes, until the NSA requests that DDG allow them to see all searches in real time. You could argue that it says "court ordered" but no one here has any clue what type of pressure the government used to get PRISM through at a major publicly traded company or what they are capable of with a small operation like DDG.
[added] as pointed out below, the NSA could and will just save the searches which would result DDG being just as insecure as google.