This sound fishy, how does he know he has been blacklisted?
There are definitely ways to find out. When I was blacklisted before by a publisher (not Sony, for the record) I was never 'officially' told, but somebody who I got on well with who worked at that company called me up and gave me a heads up. Sure enough, they didn't speak to me for 4-5 months, and then suddenly, out of nowhere, I started getting press releases from them again and they started answering my emails. Often times you can
know, because the flow of information from PR to media is so constant where if somebody always chattering at you and always trying to get you to cover things suddenly falls completely silent it becomes clear something is up. Sometimes people just get flat out told, too, but that's much rarer.
Blacklisting is way more common than people realize, I think. It happens quite a lot and it happens for a lot less than a report as incendiary as this.