Offchocks,
I fly around a fair bit and this ridiculous "no mixing" of crews rule applies only in the USA and Oz. Haven't been to the UK for a while. France definitely allows mixing.
Meanwhile engineers with leather man knives in their belts and random cleaning ladies can be on board and mix with both inbound and outbound crew. Yet you cannot remain behind a give a Saftey related technical brief to the next crew.
What exactly are these rules designed to achieve?
If if the inbound crew gave some "contraband" to the outbound crew - it would be leaving the country! So what?
Maybe, for our outrageous security and customs fees, a busybody from the concerned agency ( customs, immigration, Fed Police - I really don't know who is worried about what) could stand next to the inbound and outbound crews to make sure we only talked about technical things and not, for example, about mindless bureaucracy!
BTW Minister Albanese. I will vote for any party that brings some sense and practicality to Aviation Security but I have to say it's not looking good for you so far.