First off, I want to say that this shooting occurred about a 15 minute walk from where I went to high school. I also worked at TOPS Markets during my college years but not at that particular store. The shooter was not from the community but I know for a fact that such ideas ans the shooter sprouted does exist in Buffalo NY.
This is the issue with the extremism that is coming from both sides of the aisle. In this case, it was right wing extremism but left wing extremism is just as bad. The problem with removing these message boards is that they will simply go underground using technology such as the TOR browser, VPNs, and require a crypto payment to get into the board. It will be tougher and tougher for the FBI to police. If you don't believe me, look at the issue with child porn. What you read in the news only scratches the surface of that problem.
What we need to do as a community is say no whenever we hear anything that harms the community, even if it is our friends saying it. We need to tell them that we do not want to hear that stuff and if they continue to talk that way, they will not be our friend too much longer. We need to stand with all people when stuff like happens and say no, this will not define our community.