It did block an IGDA chair! One who had deep connections to MRA sites, responded by tagging in #gamergate to get his friends to take up his fight against this "unfair" censorship, and shortly after this incident found himself to no longer be associated with the IGDA.

System working very very much as intended there!

The only /real/ false positives it's ever generated that I'm aware of are a handful of people closely following hate group leaders to report on them, all of whom easily passed through the whitelisting process, and support the blocker wholeheartedly.