Everyone missing the point here.The ASX facilitate the release of company announcements in keeping with the regulations. That's all.
General rule
3.1 Once an entity is or becomes +aware of any +information concerning it that a reasonable person would expect to have a material effect on the price or value of the entity's +securities, the entity must immediately tell ASX that information.
Simply put, once AVZ are aware of the class action and its possible impact they need to release these details to market.