Even assuming that's true (and I don't know or care if it is), it's unclear to me why it should reflect on the community. If tomorrow somebody were to leak a tape of Paul Graham or Joel Spolsky ranting about their hatred of some race, it wouldn't somehow reflect poorly on the character of anyone with a Hacker News or Stack Overflow account.
First and foremost political opinions have no place in most professional settings and no influence on someones work. If I recall correctly it's even illegal to judge someone based on their political affiliations in many countries.
Further, someone could have an account there to comment against the radical opinions or because he has friends with those opinions, which brought him to the network. And surely some more reasons why someone might have an account without sharing the extremist views of the outliers there.