That sounds more like a bug to me (hence asking how exactly you call it)
It doesn't matter if there is a bug or not. It won't change the fact that when you press stop on the MCE remote, it sends you to standard view instead of leving the player and cleaning everything up behind it.
This is why a startup option is needed (as it doesn't seem to exist) so thatr when JRiver is launched as an external player from the command line, it can exit cleanly when the playback ends or when STOP (or BACK) is pressed.
Anyway, I've resolved the issue by changing the registry using the front end (CMC) so that the RED button closes the app (same as ALT-F4). I then programmed my Denon Universal remote (using the learn feature with my MCE remote) so that it sends a "RED" command when STOP is pressed, which cleanly closes JRiver.
So my personal situation is resolved, but I still think that there is a case for a startup switch that would achieve this more elegantly. It would make the use of JRiver as an external player much easier. It's up to the devs if they want more sales that way or not. The current behaviour is NOT good when JRiver is used as an external player. The user shouldn't have to use the workaround I've found. Plus not everyone has a universal remote with a learn feature, or a front end that can change the registry settings easily.
Thanks for your help