Insubordination = Defiance of authority? For simply being rude to another crew member?
I really don't think so. Why don't we all going back to looking after our customers and let the CSM get over it. If she can't and is consistently bolshy to the extent that it's having a detrimental effect on operations and/or passenger service, I'm sure Qantas has a disciplinary procedure.
The Captain could, of course, bypass this and go directly to CASA, tell them that aforementioned CSM refused to let his FO stow his bag in a locker and wait for their response.
I imagine it would be FO.
Let's all go back to sleep - this thread is a waste of pixels