Maybe the males might have been more likely to bite the hand that fed them in such an inconsistent way.

Interpreting all this in terms of "justice" seems a bit stretched to me. Essentially, it's a kind of journalistic PR.

I mean, if you did this kind of experiment with human beings, the kind of reasons for the results shown could include all kinds of other motives as well as a hunger for justice. And as this thread has demonstrated, even when it comes to "justice" there are all kinds of different way of determinig what is just.