This is silly. Spending time doing interviews is a part of running business and doing some prior research on a candidate helps not to waste too much time and money bringing them in only to find out they lied on their resume.
Is this legal? It can't be, right, as no agreement was made?
I wonder what the ramifications of paying are? He could now say he purchased a service, and that he got rejected was a problem with that service and demand his money back. Maybe he can get a second interview by saying he is not happy with the quality of the first interview he purchased.
This is most likely fake.
It may not be fake, but it's certainly a repost that I've seen before. (pretty sure it popped up on HN back when it did)