If the 300 room FT member wasn't ashamed of it, then he or she would have no problem posting it here. They also would have posted the e-mail on FT.

But, I don't think threatening to complain publicly if you are less than satisfied is at all wrong, so long as you are honest. It's called word of mouth. All businesses know or should know that many satisfied customers refer other customers, and that unsatisfied customers tell friends and family about it. And if the this person complained and was honest about what happened, well, it wouldn't hurt Hilton's business at all, because it's clear who is being reasonable and unreasonable here.

Finally, the operative legal term that people have been avoiding here is "consideration".
A $0 room rate has no consideration on the part of the consumer. A $29 flight doesn have consideration- $29. A bad deal for United, maybe, but still consideration? Yes.