His twitter feed is an automated news robot by the looks of it. Check it out at @PaulTully looks to me like it just trawls the net (probably just a google news rss feed for "Goodna") and spams it. The news story about the two bodies found in the house in Goodna was published online by the ABC, Fairfax and News Corp, probably all from the same AAP wire. The failure was more related to the rapid news cycle and the lack of fact checking (the story was retracted within a few hours, although some simply reported that police couldn't confirm the find initially - some even incremented the official death toll to include the 2 bodies).
This happens all the time in unfolding and tragic events like these, fact checking is a luxury in the pursuit of getting the story first. The current priority seems to be get the story first, then get the story right.
For the record (and back on topic), in 2005 a horse was attacked by a bull shark more than 20km upstream from Goodna, I hardly think its impossible for a shark to swim 600m through flood waters.