I'm thinking about the final non standard radio transmission. As this happened after the ACARS was turned off I presume that someone has done an analysis of the transmission to see if it is either of the pilots voices. The opinion of some of the comments on this site is that it is an Americanism, is it a normal term of speech for Malay pilots?
An analysis of the voice would have been one of the first things done. Being based in this region many local flight crew and even cabin crew have "Americanism" or Western slang terms. This is a result of being around many expats and some are educated in the American and British Schools in these countries.