They sent out a letter on law firm letterhead that made reference to violations of the law and wrapped up with a blunt request for a response within 24 hours. They are trying to bully the interviewer by using carefully crafted language to make it look like the interviewer could face legal consequences from not complying with the request. In fact, the interviewer has done nothing illegal and has no legal obligation to take down the podcast containing the interview nor an obligation to even respond to the letter.
This, is bad karma.