Well, in essence, all military operations can need engineering support - and the environment in which special ops forces operate sometimes require engineers who can operate in that environment themselves - they basically need to be special ops troops. That's what the SOER does. They are also specially trained to respond to chemical, biological, radiological, or nuclear attacks whether domestic terrorism, or overseas as part of combat operations.
Thank you. I noticed from reading the description of duties that the American Combat Engineers were to be used as infantry as needed.
I know of one instance where they actually were turned into infantry for a time.
I bet the same is true of those Aussie special forces engineers except even to a higher standard of training.