Well, the trouble come in the sense that the book actually uses the word "killed". As in:
"If the mount is killed, then the skink crew are killed too as they are crushed beneath the falling body."
Later, it mentions that the non- character skinks are ignored for victory point purposes- but we're talking about combat resolution, which is quite different.
If an opponent wanted to make an issue of it, I would be hard pressed to defend my side based on RAW. Good thing this came up when I was playing my brother...