“the new version of the last words is more formal and more in keeping with the way a pilot might usually speak to air traffic control than the wording previously reported”
In other words they made it up. :-)
See Uncle Chip’s posting #41. The last words, technically, were the ones from ATC, saying “good night Malaysia 370.”
They say they’re “analyzing it” to see if it was from the pilot or the co-pilot, but obviously, it was from neither of them.