I can't find it right now, but there's a YouTube video that demonstrates using this mode for astrophotography. It seems that a side effect of the computational process is that noise gets averaged out, resulting in a cleaner (and sharper, as you'd be expecting anyway) image.
In a sense, it's an in camera image stacking where the sensor noise can be removed while retaining actual image data.
The Nikon bodies were known to eat stars with its in camera noise removal worse than other makers, it was one of the reasons astro recommendations are to not use that feature for any body.
