Ah, OK. You'd only want to run the Close command if Opus was already running. Otherwise, Opus will be started so that the command can be sent to it, which doesn't make sense if the aim is just to close Opus.
The ExitOpusAndWait script in How to Exit Directory Opus - #2 by Leo has an example showing one way to check if Opus is already running before telling it to exit if it is.
The Close command only affects the user/desktop it's run from.