Yes you are right with the $ point of view, I know within the QF group there are times when apparently CAA or CASA has given certification to certain crew on the aircraft to be able to stand, eg - safety demo, arming and disarming of doors (these tasks are performed when the seat belt sign is illuminated).
Back in the days of Ansett NZ (not sure if this applied in aus), (and i know this because crew have told me here in nz but i used ot also fly in aus), that seat belt sign at certain times only applied to the passengers and if crew were required to be seated then the captain would inform them to be seated separately of crew. I believe that perhaps this method still applies to a lot of airlines, including DJ. The idea behind it being applied at Ansett NZ was the short sectors and limited service time. So perhaps from this point of view, yes you are correct. I also believe one crew member may stand up to relay jackets back to pax seated in J/C, during taxi in. This is a company policy within Jetconnect, but im not sure how it would stand up against CASA or CAA.