It has not been mentioned in this trial at all as a charge. It has certainly been mentioned that Allison's body was dumped, therefore implying the notion of interference with a corpse, but it is not part of THIS trial.
I would imagine that QPS may not have wanted to create any form of confusion or ambiguity in this trial by having to prosecute two charges rather than one to the jury. I have no doubt that once he is found guilty there would be absolutely no reason why they could not then go forward with interfering with a corpse, especially if they are thinking of charging mnore than one person with the crime.
JMHO.
Cheers.