I think the Aussies have an excellent Military, and have been a very supportive ally to the US over the many years.
I also lived in the Philippines and have an understanding of how things work in that country.
I think the Aussies are participating in the PH for the same reason that so many countries send small contingents on UN sanctioned military missions: for training, experience, and to build bridges between allies so they can work together effectively during future conflicts.
Experience with ISIS in the Philippines might help when dealing with similar future missions in Indonesia.
Again, in no way did I intend to slight Australia for their participation.