Seems really plausible, right?
The attack was set for Anzac Day in Melbourne. A 15 year old has already been charged. Nineteen-year-old Sevdet Besim has recently pleaded not guilty to four charges related to the terrorist kangaroo plot. He faces a life sentence. The two reportedly communicated via telegrams because... I guess... they really wanted to make sure there was a paper trail old school style on such an amazing terror plot?
"The conversation continues with BESIM detailing what he did that day and they have a general discussion around animals and wildlife in Australia including a suggestion that a kangaroo could be packed with C4 explosive, painted with the IS symbol and set loose on police officers."
Sounds ill-advised.
I mean, wouldn't they paint the IS symbol on the kangaroo before attempting to load it with C4?
Also, wouldn't the kangaroo quite literally kick these guys' ***** if they attempted to do that?

Or... is this the police trying really hard to prove terror is literally everywhere, including in the misguided minds of teenagers who hatch a "plot" that sounds like it belongs not in reality but in an afternoon cartoon?
Oh wait, it already was. Maybe this is where they got it from!