"You could even be minding your own business (as both the bandleader and Woltz were) and if you had something Vito wanted, he would take it under threat of violence."
I don't think they were merely "minding their own business." Minding your own business would be a store owner who gangsters go to and demand protection money. The situation with the bandleader and Woltz was different. Particularly Woltz. In his conversation with Tom, Woltz made it clear that he was denying Johnny the role because of a personal vendetta and a desire to "run him out of the business," even though he actually believed Johnny was perfect for the role. While one could argue that Woltz had a right to cast whoever he wanted for whatever reason, Johnny, Tom and Vito still had huge reason to be pissed. Although one might seriously question whether killing an innocent horse was an acceptable response, Woltz was not some poor little innocent victim that had something terrible happen to him for no reason.
Hmm. I see it differently.
It's explained more in the book that Woltz was too stupid and egocentric to recognize that Vito was playing in a different league than he was but that aside, Woltz's only mistake was not giving Fontane a role that Fontane (and Vito) thought Fontane deserved. Woltz was not beholden to Vito in any way and owed him no favors or money. What Vito did to Woltz (and whoever Woltz had given the movie role to) was exactly what Fanucci had done to Vito years before when he leaned on Abbandando to get Vito fired. It was pure extortion. It was a higher level and for bigger stakes but the principle was the same. "Give my friend what he wants or I will harm you".
So Woltz was minding his own business and through no action of his own ran afoul of Vito. Woltz certainly has the right to run his studio as he sees fit without an obscure olive oil importer telling him who to hire.
*Woltz is not innocent (in the book the crime with the young girl appalled Vito) but he hadn't involved himself in Vito's world.
** Also I think it's very likely that once Vito discovered that Woltz could be bullied , Vito (and his friends) would have expanded extortion and racketeering activities on Hollywood in general and Woltz in particular. Woltz never would have been free.
