Once you know some basic principles of photography, this actually shouldn't be all that surprising. The Google Nexus 6P uses a 1/2.3 inch type sensor that measures 6.17 x 4.55 mm. That gives us ~28 square mm of sensor area. The initial example image was taken with a full-frame camera with a sensor that measures 24 x 36 mm, yielding 864 square mm. That gives the DSLR ~30x the sensor area of the Nexus. Then with the same amount of light per square mm per second (measured by the f-stop of the lens) the Nexus needs to expose the image for 30x longer than the full-frame camera to gather the equivalent amount of light. It just so happens that this approach used 32 exposures - it makes sense that the results look comparable to a full-frame camera because the phone gathered just as much light.
This is a case where the source of the information does matter - the article notes that a number of files were edited and that tampering with information isn't new for Russian intelligence. That's not to say the leaks are false, it's just that skepticism is a prudent response.