Thank you for posting that video. The fellow looks pretty white to me. I wonder if this is more of an Adam Lanza type, young, on psychotropic drugs for ADHD or something... that’s a possibility, although it wouldn’t explain why they are protecting his identity.
He was described as having “light brown hair,” although it’s hard to tell (because of the time of day and the angle) what color it was. However, he does look like a sort of standard model young white guy of no particularly identifiable ethnic group.
There’s nothing that prevents him from being a Muslim convert or even from a traditionally Muslim European group (such as Bosnian) or even Chechen, some of whom are very fair skinned.
He could, as you say, just be a young white psycho. But it is odd that they’re not releasing his name.