I think the debate about the dfo location is irrelevant to this crash. For whatever reason this Kingair was going to crash, whether it was into the dfo or the Tullamarine freeway or houses. It was going down when it struck the building roof.
Airports cannot be made totally crash proof unless you locate them where no one will use them. The dfo at YMEN is clear of the departure splay and any argument against its presence is effectively an argument for the closure of the airfield and I am most assuredly not arguing for that.