Some argue also that the ethics of pest control require minimising pain. In other words, killing a hundred rabbits is presumably worse than killing fifty bilbies because the sum of the pain involved is greater. Those who argue against this line, and I am one, must confront their values. But these native species deserve our support not for arbitrary reasons but for empirical reasons, independent of human benefits. The argument is not about the rights of individual animals but the rights of ecosystems.
Many animals can exist nowhere but in their own environment and ecosystem.
An individual rabbit may equal an individual bilby in ethical terms, and equally deserve humane treatment, but a whole extra set of reasons exists for defending Australian animals in Australian habitats. That is all they have, and those habitats can exist nowhere else. If animals belong in them, defend them. If they disrupt them, remove them. Decisions can mostly be made without reference to human benefits and losses by using ecology, not sympathy, as a yardstick.