I'm not sure about that. I think CX has limited the CPP to HkID owner nowadays..they used to allow foreigners too but I don't think now they do.
In their (CX) application page, it says :
"Please note that we are currently ONLY recruiting for the Cadet Pilot Programme for which a permanent HKID card is required."
It makes sense because collectively as a whole Hongkong, the city wants to provide more opportunities to its own people nowadays. Jobs such as pilot r really limited, and if they still don't favor it's own people after so many years of letting foreigners to establish the company's infrastracture, it wouldn't make sense. I think CX and KA are doing the right thing now.
I am really happy that even press are saying "Hk is ready now"
Sorry out of topic, just something I'm really passionate talking about. I should not do this in interview