That being the case, for how long are Australian Citizens expected to be denied their constitutional right to travel to WA without being penalised because of the state in which they live?
As long as the WA government can prove there is a threat to public health restriction of movement is perfectly legal. If you can prove otherwise you can force them to allow freedom of movement. International law on human rights and our constitution allows restriction of movement for public health, public order or to protect others rights. No point quoting constitutional rights if they don't apply in current circumstance. It does not even have to be a public health emergency, that just makes the case stronger for the rules.
That's why the protesters are double morons, if they create civil disorder they give the state further power to restrict movement.