Just checked my statement from Chase.

The Al Molo Harbour City charge, through a Global Payment terminal, is DCC-free.

Got my currency confirmation slip showing HKD, through post facto DCC opt-out.

So I really think the Global Payment terminals in HK have this feature to select currency, but managers or cashiers don't know how to run opt-outs, or aren't given the credentials (or didn't ask for them) needed to run opt-outs...