It's true that FTs are displacing Singaporeans everywhere in SIA, even as cadet pilots. That's because SIA doesn't care, as long as they find somebody who fits the profile of a pilot that the company wants. And it's not in sinkies advantage that we are known as a whining and unappreciative lot.
If a FT is employed as pilot, even better! The company saves money on CPF contributions. You can tell this fact to the idiots who say Singaporeans and FTs on local terms have the same salary package in SIA. No FT in his right mind would give up his citizenship to be a Singapore PR just to get some miserable CPF when his salary in Singapore can buy him easily a mansion back in his country (boleh land). So it is much cheaper for SIA to employ FTs on local terms than Singaporeans and many of them remain on work permits even after being promoted to captains.
For cadet pilots, they generally look for some kind or hint of achievement in your resume even before they call the guy in for the interview, i.e. involvement in sports, uniformed groups, debate team, charity work etc etc. Yeah, and having good grades help. They want to make sure the guy will make it through the training proper and not some joker who will get chopped anyway.
So for guys who went to the interview with SIA and didn't make it, unfortunately it means you do not fit into the profile that SIA wants. It is pointless to then try to buy your way in by paying through your (or your parents) nose for a private license.