You may remember in the initial PEY rollout, CX was quite aggressive but in the end removed a row of PEY from the A330s, and then removed PEY from some otherwise long haul configured aircraft. These also fly to India. But many passengers from India fly on to USA and not other places in Asia. So I'm not sure this bolded sentence is the reason why there isn't PEY to Dubai - it just seems like that market doesn't work.
Interesting. I have been wondering why CX has not changed equipment on this route to 77W and had been assuming that the 330's lower weight must offer better economics given the BAH tag. CX seems to operate PEY on plenty of shorter regional routes where demand is limited/questionable.