Earlier quoted context omitted.
I do not vet the politics of all my co-speakers. That said, if my black friends are dropping out of a conference because they feel deeply uncomfortable even being near someone, that's as clear a signal as I'm likely to get that something isn't right.
Why not? For all you know, you might be attending talks from raging Nazis or hardcore Stalinists or people who think government-mandated key escrow is a decent idea. Is it only a problem if you know about it?
https://medium.com/@codepaintsleep/lambdaconf-2016-controver...