Maybe on the part of the popos, but DEFINITELY NOT on the part of the Jihadi.
Correct - it’s referred to as a siege because the police contain the events. That is what happened. The word is correct. And even if it was originally incorrect, it’s been used that way in English for at least 100 years (see the Sidney Street Siege of 1911).
The statement should have faced reality in today’s world and Australia should acknowledge self defense against these violent Muslims and other common street thugs and murderers by allowing concealed carry by non jihadi law abiding Aussies to stop those who would kill the common man.