If a person is committing what can reasonably described as acts of war against a nation that they are not physically present in and the government of the nation that they _are_ present in declines to punish or extradite the individual, I think it's reasonable to regard that individual, and the government protecting them, as being in a state of war with the nation against which those acts of war were committed. That being the case, I would regard the individual as being subject to retaliation by the nation that they are at war with.
That, however, would be a very different scenario than an individual against whom all civilian legal avenues have not been exhausted.
You might want to find out which UN treaty you're talking about and actually read it. Pay particular attention to the word "directly"
Convention and Protocol Relating to the Status of Refugees
"1. The Contracting States shall not impose penalties, on account of their illegal entry or presence, on refugees who, coming directly from a territory where their life or freedom was threatened in the sense of article 1, enter or are present in their territory without authorization, provided they present themselves without delay to the authorities and show good cause for their illegal entry or presence."
Australia doesn't get a lot of refugees coming from Indonesia, Papua New Guinea, Malaysia, the Philippines or New Zealand.
What's more, it is, in fact, illegal and the convention calls it illegal on more than one occasion. Contracting states are, however, forbidden to penalize people who enter illegally provided they present themselves to the authorities promptly.
He who steps on others to reach the top has good balance.