So when do people who take hostages and carry out a seige go from being criminals (like those Waco dudes) to being terrorists?
They're terrorists when their motivation becomes political (as opposed to personal gain).
But either term is good - it denies them legitimacy. Unfortunately 'terrorist' is a bit overdone these days. Welcome to the age of terrorism. I blame camera phones and social media.
Anyway, this won't be resolved without blood. If these idiots don't get their radio interview with Abbott they will start killing hostages. They should be aware that killing hostages is a trigger (though if they do it quietly with knives they should be able to get most of them before the cops realise and go in noisy).
These guys will be aware the government probably won't give them media time, and they are almost certainly prepared to die (or they were when they woke up this morning). The main goal will be to create a high profile incident (cheers, media), and that objective has been achieved. Hostages will die and some organisation will claim responsibility and tweet that Abbott is to blame for refusing the radio interview.
People that already hate Abbott will lap it up. Welcome to politics.