He didn't literally mean 'right' as in legal or moral right---he meant logically it makes no sense. it's just a cash grab due to the fact he was a tangential part of something that happened 46 years ago.
It's like someone who hung around the set for 3 epiusodes 45 years ago deciding to right an autobiography as if anybody cares about him. Nonsense, they are just hoping for a minor tidbit of info he might have to offer.
The guy could just have blogged or tweeted a little info and it would have been better.