There were token numbers of expat trainers and checkers. A few on each fleet. Some expat chaeckers can be arseholes too....sadly, most checkers and auditors had not much previous training experience in KAL and generally suffer from the " small man " syndrome. I remember one Aussie checker on the B777 who was such an arsehole...poor system knowledge and poor experience but an ego the size of 2 football fields. Heavenly intervention prevented him from causing further pain. Hopefully his close shave with big C mellowed him into decency.
I think the guy who rejected instructorship was a Chinese guy, not Malay. If I am not mistaken, he resigned earlier after they screwed him over the fuel leak incident.