First of all, I'm NOT a mom, and I couldn't care less about soccer. And it's NOT B.S. From the article:
he had pulled out the Scream mask from his shoulder bag just before he started stabbing her.
This seems to be an indication that the teenager, Julien, was INDEED influenced by the film. Sure, maybe he had an innate propensity for murder, and maybe it WOULD have shown up later, but in this case, his fascination with the film cost a young woman her life. Even if his propensity for murder DID emerge later in life, without that film, THAT particular young lady would still be alive.
I'm trying to be polite and diplomatic here, despite the fact that your comment was rather rude and caustic, stating that a true conservative could not believe that film violence can be influential to causing violence. You're painting with a mighty broad brush stroke here.