You don't need to be Green for opups. A friend of mine (actually the driver of my friend) recently got oped up on his very first flight with Cx with only Asia Mile membership from PEY to J Hkg - Syd.
Y must be very oversold (that's why his boss had to book him PEY) and he must be the only single pax left after all the elite pax in PEY been upgraded.