For those of you who say the employee is in the wrong, fuck off. When jobs take weeks to initiate the first interview, to the sheer number of interviews, to being passed over and getting to the last interview to be told no, there's zero expectation as a hiring manager that the employee hasn't received multiple offers. You hope that your offer is the best and they decide to join. To those also saying this is an inconvenience to the employer, sure, but that's why you go with the 2nd choice and move forward.
I don't know the employment laws where this person was, but where I am, it's a right to work state. I can quit at any time with zero warning. I can also be fired at any time with zero warning. I used to do hiring, and for someone to get so ass hurt that they publicly shamed the candidate is insane.