Command line switch to disable Coherence?
It's funny that you should ask about this. There are other requests for the same (e.g. some sort of command line flag to "disable" Coherence), and I believe that it is planned for an upcoming release (either the currently-rolling-out 12.1.3 or the following release).

Is there anything in specific that you see Coherence "doing" that you're trying to avoid?

(Disclaimer: I work at Oracle, including on Oracle Coherence.)