Just a few years ago, a guy posted an anti-immigration/white nationalist manifesto online then walked into a Walmart in a predominately Latino area and shot 45 people, killing 23, almost all Latino.
The Christ-Church massacre killer also posted an anti-immigration manifesto. The kid who shot up the Colorado school an hour after Charlie Kirk died also was a far-right white supremacist.
Also, we still don’t even know the valence of the “fascist” engravings. The Groypers movement - to Kirk’s right - commonly referred to Kirk as a fascist. The Groypers also re-appropriated Bella Ciao for their politics. It’s on all sorts of far-right music playlists online. All the major newspapers have quietly retracted their claims that the kid was left-leaning after their sourcing turned out to be bogus. The text messages you cited earlier were fake, for example, as well as the supposed discord messages.
Of course, no matter what we find out, you’ll refuse to believe it if it isn’t what you want to believe. And that’s the whole reason why the Right immediately ran with it and shouted that it was done by the left. They know their supporters well and that the truth doesn’t actually matter to them.