I don't really like SMAS graphics. They just look so weird lifeless and desaturated. Even NSMB looks a bit better, but it's too plastic (come to think of it now, SMAS also has kinda plastic look to it)
Maybe I overreacted a bit, but take a quick look at 4chan's /pol/ or some of the alt-right subreddits. It's so sickening and this sort of content definitely isn't worth protecting or defending. Also freedom of speech doesn't apply to websites. And it doesn't protect people from consequences of their words. Youtube for example already takes down a lot of videos and punishes some channels for the most trivial shit, but when the shadiest channels generate the most revenue, they usually won't bother and turn a blind eye to them. And remember that who is popular is largely influenced by Youtube itself and its algorithms, so it's not like they don't control it already, if you are going by the censorship argument.
Back to pewdiepie, when first, white supremacist websites applaud him for making millions of viewers comfortable with racist ideas and then a terrorist with these views mention his name, it is his moral responsibility to distance himself from it as far as he can. Especially when he has so much influence over people, many of them young.
I would like to add that the terrorist was strongly influenced by the conspiracy theory of The Great Replacement. Such conspiracy theories (and there are a lot of them, some more harmful than others) have so much visibility and following in the age of internet that it's absurd. You are talking so much about censorship, but haven't you thought that some of the harmful ideas propagated their way into mainstream though means like memes and algorithms that only care about engaging content, not truthful content? Think stuff like flat-earth but way more harmful. Or anti-vax. And thanks to these influencers and algorithms and other social and internet-related phenomena it's so easy to fall into these rabbit holes. Just watch some anti-SJW vs SJW stuff and see how long until Youtube recommends or autoplays some fearmongering videos based on conspiracy theories like the ones that scared the terrorist into doing this with no regrets. Because yes, he was also a coward and an irrational one. Or just simply go search for some memes, stumble into 4chan and discover /pol/. Or even reddit and that type of subs.
Regarding PDP, while I certainly don't consider him the main person to blame or something like that, he can be a sort of gateway into this content. And while that isn't entirely his fault (as it also partly falls on Youtube and other parties), he should certainly be more aware of it and realise his responsibility.