"Hey, fascist! Catch!", "Bella ciao" and three arrows are all antifascist. I would assume that the shooter is motivated by antifascist political ideology at odds with Kirk's political ideology.
The groypers are not antifascist, so the reported symbolism doesn't add up. If there's evidence of the shooter being a groyper, then I'm curious to see it.
Ok, the song exists on a playlist with a few hundred saves. I don’t think it’s a widespread groyper meme though. I’ve never seen them reference it on Twitter.
Maybe the arrows are a video game reference? I still don’t see a groyper tie there.
Meanwhile mainstream sources are reporting that the shooter appeared to be motivated by left political ideology.
You seems to be trying to cram this into an inapplicable left-right frame. This is intermemetic warfare. That's why major newspapers need extremely online editors to fact-check their reporting.