Agree on all points. I had mixed feelings that the fact that the population struggles in the face of poaching despite having no effective natural predators seems conducive to fostering a controlled population in a closed environment. The food chain wouldn't affect how they proliferate .

But the first thought is always...just the track record. Rabbits, foxes, cats, cane toads, donkeys, camels, goats, pigs. But, like you say, they aren't going to be losing track of their rhinos.

But, arguing conservation as a practical application, has Australia ever intentionally introduced a species for a practical application and had it not go absolutely sideways (big caveat, usually once the animals escaped, or were just turned loose)?