So, I finally got a chance to test this out. I did not change the DefaultEngine.ini and packaged the project, instead I placed the above information into ./ProjectName/Config/UserEngine.ini and now the project worked for a shipping build.
So, I think this resolves the issue. The command line settings that Switchboard sends out are actually dev only commands, thus the engine ignores for a shipping build.
If you want a stand-alone, shipping build to work with nDisplay, the UserEngine.ini needs to have its settings set -OR- you need to package the project via the DefaultEngine.ini file with the same settings for nDisplay to start up. You can’t pass how to modify the Unreal engine to start up with different classes via the command line, like how Switchboard does, when packaged as Shipping.