The thing is, the shooter made it clear why they chose to reference PewDiePie. They wanted the media to take the bait, blame PewDiePie, and escalate the culture war. There doesn't really seem anything to suggest he was inspired to do the shooting because of PewDiePie.

What the fuck is this bullshit. PewDiePie didn't find himself being a "symbol" of White Supremacists funny, he found the media trying to piece together hitpieces on him by trying to connect him with these groups funny, because it's not true. Learn to realise not every accident someone does (like the livestream or Fiverr incident for example) is a Freudian slip. If anything, the media painting him as this "powerful hate-figure" is attracting these people to latch onto him.