I personally know most of the reptile keepers at Melbourne Zoo and have seen all of their off-display stuff a few times, sometimes without any notice that I was coming. They are definitely at the top of their game and all their animals were in superb health. In a single half a day visit, I witnessed them retrieving freshly hatched Delma impar's (an endangered legless lizard from the grasslands of south east Australia), a beautiful Fijian Banded Iguana laying eggs and a big healthy Frilled Lizard preparing to lay eggs.
I haven't seen any other areas of the zoo (how's that for being dedicated to reptiles!), but from my experiences with the reptile department, I find it highly unlikely that any of those allegations are based on truth.