First, magnifying the shooters manifesto and spending time on it, is effectuating one of his goals. I'd rather not. But since we're getting into it, the entirety of the rambling is a mixture of shitposting and views completely incoherent with one another (likely intentional considering his stated goal is to incite more division and war). For example, he spews classic white supremacist link and rails against conservatives (essentially the ultra-rightists version of a leftist saying some claptrap like, "liberals get the bullet too"), before endorsing CANDACE OWENS as his biggest influence.
He wants sides pointing at the other. Don't give this poopchute what he wants.
The problem is, there are people defining wholly benign talking points such as "we need an immigration freeze from countries who can't get their excrement together" or "we need a secure border" as "politics of hatred." Pewdiepie is now being cited as some sort of gateway drug to white supremacy, which is absurd.
I completely agree with you that reasonable discussion about sensitive topics has become exponentially difficult as a result of the screeching overreaction to pretty much everything from the more extreme sides of any debate, but it doesn't mean that we shouldn't still try and have it.
However, I don't think that any debate is enhanced by Youtube "personalities" passing off nazi salutes as just a joke. If you have a platform, inherited or built, you have a responsibility to use it in a fashion that is beneficial, and if you choose to use it in negative fashion then you should expect people to want to tear it down.
"It's only a joke bro" (I know you didn't say that) has become one of the most counterproductive and unpleasant mottos of a generation IMO, serving as it has to excuse behaviour that if you did it in person would get your nose smeared across your face. I find it difficult to reconcile people demanding that we stand, remove our hats and pay respect to a generation that gave everything while at the same time accepting that a nazi salute is simply an expression of free speech. If my grandfathers and likely any of our grandfathers who served had seen such a thing while they were alive they would have filled someone in for doing that, and if they didn't I'd have done it for them. The end result of "it's only a joke bro" is 49 people gunned down in the name of bigotry.
Ignoring this excrement isn't working.