I respectfully disagree. Beyond the reason that there is no way you can be 100% certain 'unmoderated media' was the primary motivator. Nobody can presume to know his motivations or inner dialogue. A look at that mans history shows clear mental health issues and self-destructive behavior so we can infer some things but never truly know.

Violence exists outside of mean tweets and political rhetoric. People, even crazy ones, almost always have their own agency even if it runs contrary to what most consider to be normal thoughts and behavior. They choose to act, regardless of others and mostly without concern or conscious. There are crazy people out there and censoring others wont ever stop bad people from doing bad things. If so, then how do we account for the evils done by those prior to our inter-connected world?

We really don't know much. The attacker used drugs, his ex partner said the he went away for year and came back a changed person.

He lived in a community with BLM signs and a rainbow flag. He did hemp jewellry.

He registered a website three months ago and only recently filled it with standard extreme right garbage.

This is all so odd that for all we know someone else radicalized him offline, the old fashioned way.