But surely, in arid timber ecosystems, wildfires are natural?

Yes, but there is a difference here. She started it by burning paper during an absolute fire ban, and it quickly got out of hand. Out of all the wildfires in this state this year, only a few have been natural. The Hayman fire is a huge mess due to it being a really windy weekend when it started. Most of the fire spread happened in the first two days, the days it was up to around 1-2 miles per hour. Had it been natural, it would have probably been started by lightning, something that area hasn't seen for weeks.

Sure, it's going to be a while before that particular land area burns again, but due to her actions, the fire ban turned into a closure of all the parks in the area, and it will probably last the entire summer. It also caused firefighting resources to be strained in the state, instead of a natural fire happening at another time. Had she not stated this one when she did, the coal seam fire would probably be out now, and more resources could be dedicated to the one burning out of control in the south western part of the state.