My line of thought was the exact same as yours based on what the media reported until a few days ago when I was told about matching circumstances of the incident from different sources, circumstances that completely tie in with why its a manslaughter charge for Barry.
The media have irresponsibily whipped up hysteria and tensions through '2 + 2 = 5' reporting, through misinformation and a failure to report on a wide range of critical circumstances that led to and resulted in the stabbing. The result of the media's reporting upon the wider public is seen in this thread - that's not a dig at anyone posting here because until a few days ago I myself was deeply upset and angry at what I believed was a vile racial murder of an innocent kid.
The manslaughter charge is the best indication of what I'm talking about without leaving this site open to legal difficulties.