Interesting that PL is still considering their course of action. It seems to me they and the Langham have an opportunity to generate lots of goodwill here. A compromise similar to other companies' recent decisions would make a lot of sense. Something like one reservation per person, with a three night maximum would be viewed by many of us as a great response. If I were them, I would not extend this offer to those who booked by changing the URL after they pulled the offer.
How many people with a res would really show up? I can't imagine it would be more than 100 or so, and I suspect it would be something like half that. Even with 100 bookings, that's 300 room-nights. At A$250/night, that's A$75,000, or A$37,500 each. It doesn't seem like a lot of money to spend to get a great image with a bunch of frequent travelers. Those costs also don't include additional nights that we'd book - I'd certainly be good for one or two.
All companies make mistakes. The reaction to the mistake provides a look at the true character of the company. One can step forward, accept responsibilty, and try to make it right, or one can make excuses and dodge blame. I know what sort of company I respect and do business with.