The operative word being "seemed." Ray Cash wasn't the only one who was made out to be an asshole...
"Johnny's father, Ray Cash, appears in the film as cold and verbally abusive. Kathy Cash says that's unfair to her grandfather.
"He wasn't the sweetest person in the world back then, but …. Dad did have his problems with him. Some of it was true, some wasn't. It was blown up to high proportions."
Again, John Carter Cash doesn't necessarily disagree.
"The fact of the matter: If there was angst between my grandfather and my father, it was unstated. My father never showed anything but tolerance, love, patience. … I never saw him talk back to (his father.) That's the reality.
"But to shed light on who my dad was, some of the struggles between my father and my grandfather were dramatized. And I do think it was necessary for the movie."
John Carter Cash concedes overall that there are omissions and dramatizations, but that they were necessary to tell the love story. "Nobody can ever see totally eye to eye. I respect the film for what it is, and I love it for what it is. There are great holes. And there are solid fans who'll say, what about this and what about that? Look for one thing: Look for their love. Look where their love lasted. That's the message."
http://tennessean.com/apps/pbcs.dll/article?AID=/20051110/ENTERTAINMENT04/511100396/1005/ENTERTAINMENT04