Hotels jacking up rates

The Menen is upping their nightly rate from ~85 AUD to ~120. They did this while I was in the middle of planning my stay: I was quoted the first rate, then when I had to shift my plans by a day or two, they said OK, but here is the new rate, non-negotiable. Similarly, the Od-n Aiwo told me in an initial email that their rate was now 100 AUD, then a week later that no, it's now 110.

Not sure what's going on but it seems a tad manipulative. I'm planning a much shorter stay there as a result, if I go at all...

Well, it is very much a sellers' market, isn't it?
They know that you have only 2 choices: pay whatever they want or don't go.
And they must have concluded that whoever is prepared to fork out hundreds of dollars for the airfare and the passport stamp, will also pay their rates.

Yes, that does seem to be their reasoning. Of course we always have option 3: go, but for a correspondingly shorter time. I was going to spend a week there. Now, not so much...

A week???
I am pretty sure a full day would be enough for most people.

You're telling us that you make the way to go to Nauru yet you're cutting the stay short over $60.00 AUD!!! Well first of all a couple of days in Nauru is plenty, number two The Menen Hotel is practically the only place to stay there so you're at their mercy unless you find a family there to take you in their home.

"I'm telling you" that I personally dislike "bait and switch" tactics. YMMV.

Besides, other people might want to know the rates are higher than listed elsewhere.

I'm sure a lot of people don't like the "Switcher-Roo on You" Tactics, I don't care for that myself. Don't take it personally that's just the way some people are then if I really don't like it I tell myself this...."The best way to deal with people like that is not to deal with them at all." Unfortunately you might've had no other alternative at that point.Be happy that you visited the smallest republic in the world that a lot of World Travelers make the "Out of the way" excursion to get there.