Qantas Group Policy is no idle chit chat from the jumpseats......plenty of time to chat to the SLF during the flight. The only reason that the crew are there is for emergency situations and during taxi, take off, descent and landing are the "critical" phases of flight where "review" is imperative.
At Qantas you would be performance managed for engaging in chit chat to other crew or passengers when on the jumpseat during these critical phases.
its not about being friendly or unfriendly ...just professional