Notice he wisely directs his answer at the policy, not the man. This is nothing like what Howard just did. Not to mention GWB was responding to a direct question. Howard served this crap up himself, didn't he?
Latham had been mentioned in the question, so President Bush didn't need to name him for everyone to know who he was talking about. Also, unlike the US at the moment, there was only one possible alternative Prime Minister, so there was no need to differentiate.
And the Prime Ministers comments were made in response to a question in an interview on Channel 9 Australia.