I totally agree with Billy, as he used the Superstar Billy Graham name long before he went to the WWF/WWE. 

Why do the McMahon's feel like they have to own everything, even after they let wrestlers go?

Billy selected his ring name as a tribute to the famous evangelist Billy Graham, at one of those revival meetings he had converted to christianity.  

Billy added "Superstar" to his ring name after hearing the song "Jesus Christ Superstar." Sometimes he was simply referred to as Superstar Graham to avoid confusion with the evangelist.