Not too shabby at all. Was that just regular noise reduction?
I went to check:
In camera, high iso noise reduction "off"
raw compression "high efficiency" not sure if this has influence on the image's noise
shot in monochrome
everything else "off" by default
On NX Studio, contrast +1
straighten +6.0 (this was more tilted than usual

)
noise reduction "original value" so...off
lens correction "lateral aberration" was selected, I don't remember doing it...
That's it. Pretty much straight out of camera. The camera has been updated to the latest firmware and the image was developed in NX Studio.