The reality of life in Australia is that, if you are Aboriginal, you are vastly more likely to be abused as a child, you will die on average a decade earlier than the rest of the country, and as far as anyone can tell, much the same will be true for your children - life could be a little better for them, because the gaps seem to be narrowing, but they aren't narrowing fast enough to reach parity before those children reach adulthood. This is an uncomfortable truth for most Australians to hear, but at least it's talked about. What isn't widely talked about, and what is even more uncomfortable to a lot of people, is that poverty/abuse/anti-social behaviour can be passed down to kids by parents, and that this is why they are cycles.
It's hard to draw a line between pointing out uncomfortable truths in an effort to help, which I consider the role of a political cartoonist, and just slandering the Aboriginal people, which I consider racism. I give Bill Leak the benefit of the doubt because the policeman is Aboriginal. If the policeman was white, I would see the cartoon as blatantly racist, but I believe Leak deliberately made the policeman Aboriginal to contrast the two men: the successful policeman futilely trying to pull a kid out of a downwards spiral, the alcoholic absentee father unable to help, and the son who's already begun to inherit the problems of his father and might one day be in his father's position.
Even if I've read the cartoon correctly, I don't think it was very good, since it clearly failed to communicate its message. What I think of when I see it, though, is one of the Koori kids I went to primary school with, who we'll call Eli. Eli's father was jailed for drug trafficking when we were young, and didn't come back to Eli's mother when he got out. Eli himself grew up to be jailed when he was in his early twenties, after an assault related to drug trafficking, and Eli has a kid on the outside just like his dad did. Racist or not, effective or not, the cartoon accurately shows the process by which Eli ended up in jail.