yeah it's great that you have an active imagination about the motives and eventual contribution of illegal immigrants coming to australia, but that doesn't change the fact that we have laws and procedures to govern the movement of people into and out of the country, and illegal immigrants blatantly ignore these rules and so obviously do not respect our sovereignity.
If a country is a signatory to the UN Convention on Refugees, then asylum seekers are legally allowed to show up on its doorsteps by whatever means they like, without visas or travel documents and claim asylum. It is not illegal, no matter what Howard/Hanson et al may say.