There's a pretty big difference between calling someone an idiot and using sexually violent language to intimidate and pressure someone to be quiet.
As with most good laws the serious offense statement leaves room to move as society changes without having to micromanage the legislation. Serious offense is also likely defined by existing case law. Could it be abused? Of course. That's always a risk with any legislation.
And it's pretty damn unreasonable to imply that they'll be getting 3 years for this. Unless this person has a history of convictions like this they are likely to get a fraction of that if any prison time at all. Especially if it is a first offense. Australia is not the stupid US when it comes to this stuff.
One thing you can do is put an encrypted volume up as a file and then wherever you go use something like TrueCrypt to access it. Thus if someone gets access to the cloud storage they can't get easily access to the data.
In the long term what these companies need to do is tie the password into some decent encryption so you cannot access the data without having the password. Like how LastPass does things.
When parliament went into urgency yesterday the Section 92A legislation was put on the docket as a seperate piece of legislation. The only connection it had with the shit earthquake legislation is that they were both put through under urgency.
Otherwise they were entirely seperate pieces of legislation. For example the S92A bill could have not passed while the Earthquake bill did.