Total crap QF Boi - the person who told you this MUST have been drunk!
Irrespective of how many members JQ does/doesn't have, there has to be a vote among the Flight Attendants as to whether or not it's accepted, because the FAAA are a party to the Agreement (and they are the representative group of the employees).
It would be a VERY different story if we were on individual contracts/AWA's. At least with an EBA, we can decide our fate collectively, rather than having crew compete against one another within the same company for a better deal!
On the contrary, it's my understanding we have a hefty membership base! Since we became JQ, a number of people in SYD have apparently joined up in protest at how things have panned out for us.
Anyway - why wouldn't you be a member? It's a tax write off at least! More money come refund time!