Installing Nikon Capture NX2 on 10.12 Sierra
I had the same issue when I upgraded from Mavericks straight to Sierra. Capture NX2 broke. However, I had earlier installed Capture NX2 on my wife's computer running Yosemite. In desperation I copy pasted the program from her computer to mine and it is now working in Sierra. This was more by luck than design so I cannot guarantee the same results. 

The process I followed was: 


Disable SIP (system integrity protection). Please check online how to do this. It can be re-enabled later. This step may or may not be necessary but it was what I followed. 
Uninstall everything Nikon related from Sierra first. Make sure you clean up any Nikon associated files from HD/Library/Application support and HD/Libraries/Preferences in Sierra. This will have to be done manually. 
Then copy paste from a Yosemite computer running Capture NX2 2.4.7. The folders and files I copied were:


The NIKON software folder from Applications to Applications on new computer.
Copy the Nikon folder from /Library/Applications Support (It contains a Nikon sub folder which in turn contains a further six sub folders) to HD/Library/Application Support on the new computer. Subfolders in Nikon folder are listed below: 

a Capture NX 2 

b Common 

c OptionalPictureControl 

d Picture Control Utility 

e Profiles 

f Uninstaller 
Copy all Nikon related files from /Library/Preferences to HD/Library/Preferences on the new computer. These files are listed below:

a Capture NX 2.plist 

b jp.co.nikon.MCA.plist 

c jp.co.nikon.MCA2.plist 

d jp.co.nikon.Nikon Message Center 2.plist 

e jp.co.nikon.UninstallCenter (This one is a folder)



Thats it. I was surprised it worked as it was a last ditch attempt. I had tried all the other methods I could find on the internet without success. I hope this works for you, but as I said earlier this was more by luck than intent. 

I had read online that users who gradually updated their OS incrementally though the various iterations of OS X retained Capture NX2 functionality. Skipping iterations especially after Yosemite was the problem. 

NOTE: It is crucial to have this working on Yosemite before upgrading to later versions of OS X.