Does he actually promote his ideas at tech events?
From his personal statement about lambdaconf, at http://degoes.net/articles/lambdaconf-inclusion :
> Politics of any sort is out of scope at a functional programming conference. I pledge to treat other LambdaConf guests as if they were colleagues at a large company or fellow students at a university, and neither utter nor show any content that’s out of scope or otherwise disturbing. My pen name has been “doxed,” but professionally I behave as if it was a secret.
Claiming politics is out of scope is absurd, and is a rhetorical mechanism designed to, at a minimum, preserve the status quo. His politics are abhorrent -- accepting his declaration of them as irrelevant when they're anything but is effectively siding with them.
(You might argue that this isn't technically violence in itself, but it's hard to argue it's not an explicit endorsement of a system of violence.)
I'd bet that the adjacent commenter's idea of "[his racist advocacy] is well documented" comes from Twitter and Tumblr quotes taken out of context, cyclically retweeted in outrage.