I mean it might've been racism if it was because he was white. Maybe it was. We don't know his motive. Doesn't make a ton of difference, trying to stab people to death is bad either way. It's a good thing he got clobbered by the public and put on trial for murder.
What is "blatantly racist", would be racially motivated actions, like, for example, choosing to burn down the house of someone because of their race while shouting "[example racial slur]'s go home", like what the arsonists were doing. You can't really get much more objectively racist than that.
Sometimes when people call something 'racist' it's some woke snowflakey microaggression shit about like cultural appropriation or something. Setting someone's house on fire because of the colour of their skin is not that, it's actually really serious, it's like the least not-racist thing you could possibly describe.
Though much like stabbing someone, it wouldn't really exonerate them much if they set fire to people's houses for no reason instead of a bad reason, they're still setting fire to people's houses.
If the same thing happened to you or anyone you love and care about, and I don't wish that mind you, would you blame yourself or your friends for almost being beheaded or would you blame the person who actually did it?
I would blame the person who actually did it, and not, for example, any random stranger who might share a skin colour or past nationality with the person who actually did it. (Or, indeed, who might share any skin colour or nationality other than my one that I have myself)
I'd probably want to beat him with a stick but fortunately someone already got that handled for us.
There are more than two Things in the world
The people setting houses on fire, the entirety of northern Ireland, and the victim of the attack are not the same person, just as the way the attempted murderer, the random immigrants getting their houses set on fire and literally-anyone-in-northern-Ireland-who-isn't-white are not the same person, they aren't the same *thing*, they're actually separate ideas. Six ideas, not two ideas. Moral blame doesn't pass freely between them, you can't get revenge on one person who wears a red hat by beating up a different person with the same middle name if that person with the same middle name is not *actually the same specific individual* with as the othe rone, because crimes are committed by individuals, and not by middle names, not by Traits. You can't get revenge on a Trait.
If one were to locate the house of the actual attempted killer and burn that down, that might be kind of based, though who knows if he actually has a house, and it'd probably see better use being lived in by someone else since he'll be busy serving a life sentence.
One would hope this might be common knowledge, but c'est la vie.