This bill does nothing to prevent the kinds of things it is intended to prevent. The apps this law targets were engineered specifically to prevent this kind of interference. The idea that passing legislation will suddenly change that, magically allowing decryption of messages is beyond idiotic.
The legal and technical barriers to getting anything useful from this legislation are huge. Not to mention the ease with which this can be bypassed (run OpenVPN and IRC on an overseas server, done).
The justification for rushing this was so that Australia could be kept 'safe' over Christmas. It's beyond difficult to describe how ridiculous that is.
Edit: Sorry, I also have to add that in the same sitting of Parliament the government also filibustered legislation that would have enabled medical evacuation of refugee children from child detention on Nauru. It's been a bad day for Human rights in Australia.