Regardless of whether or not he's islamic, his religion is a completely irrelevant to the article. It's kind of like saying "Ten-toed butcher slaughters his wife and sells her meat." Like, it's a descriptive fact that he has all of his toes, but what does that have to do with him killing his wife and selling her meat? Same thing with his religion. Not to get all SJW-y, but I think you'd be hard pressed to find an equivalent article that says in the headline that a killer was Christian (excluding like a priest or something gnarly like that) or atheist or something.