Someone wasn't paying any attention?
A couple of locals got away, sort of, in a similar collision a few months ago. 1st rider slowed for a turn. Second rider slowed. Third rider didn't. T boned the first rider.
Beyond the basic overview, I have no further details. I suggest the only obvious inference is that the 3rd rider didn't see what was happening ahead. Why? You'd have to ask him.
Both bikes totalled.
1st rider escaped with some fractures.
3rd rider was airlifted to hospitals, ending up in Sydney for an extended stay.