"If you were going to build a piece of social software to support large and long-lived groups, what would you design for? The first thing you would design for is handles the user can invest in. [...] It's pretty widely understood that anonymity doesn't work well in group settings, because "who said what when" is the minimum requirement for having a conversation. What's less well understood is that weak pseudonymity doesn't work well, either. Because I need to associate who's saying something to me now with previous conversations. The world's best reputation management system is right here, in the brain.[...] If you want a good reputation system, just let me remember who you are."
I am not sure what the problem is that you are trying to solve, but full anonymity will undoubtedly cause the HN community much more headache than whatever you believe is afflicting is now. Whether there is a "PG bias" or not, he is accountable for his words because they are associated in a persistent fashion with his login.
One final point, I don't know about a pg bias, but I certainly have a positive nickb bias, because he has submitted so many good articles, I will normally follow whatever he posts even if I am not thrilled about the title. Doesn't mean I vote him up no matter what, but making the submissions anonymous would remove an important signal/attribute.