of course Australia can judge whether it is worthwhile to play, for starters, the tour concerns the well being of the players, and one must open their mind and think outside and beyond the concerns of cricket.
Yes Australia may be obligated to play, but i think its necessary that they send a message over to Zimbabwe. Compared to the violation of human rights, the issues concerning cricket aren't much.
I think that there is a lot of things Zimbabwe need to get right before they start looking at cricket. It disgusts me how they think they deserve to play the game, when their nation is in the situation it is. Fix it