It is a verbal promise, not a contract. They just broke it.
They were unprofessional.
A verbal promise can very easily be interpreted as a contract by a court. (IANAL, and clearly YANAL)
The legal side is almost irrelevant. The situation is that they're trying to initiate what should be a mutually-beneficial, longish-term working relationship. Leading into it with this kind of letdown isn't a good start.
The commenter hadn’t even done the interview yet. There’s no way a court would interpret this as a contract to pay the person that amount.
The only reason it's not a contract is because the job offer wasn't closed yet. This is more similar to false advertising.
The hiring company just counters they "can give X" for an imminently qualified candidate but after the interview process they feel the candidate has too little experience or aptitude and is being offered a job in spite of their shortcomings and should be so happy with the offer.