They are not acting in kind. They are not being sent back unsupervised on a shitty boat which may sink or be boarded by pirates, or anything remotely resembling that.
You seem to have a mental block to understanding the issue. As people have repeatedly pointed out, they are being flown back ie. by plane, and treated, fed and housed very well and above all transparently, with many different authorities observing, because of the high profile of the whole thing, and because the Australian government does not want to lose face on the issue. The Government will ensure their fair treatment.