If your community is having a discussion on a topic, such as whether to have a code of conduct and which one to adopt, how can you prevent external groups unrelated to the community, such as GamerGate, from joining the discussion and making the discussion far more voluminous and unproductive than it needs to be?
We could try asking the external group to change its behaviour. I don't think that's likely to be effective. I suppose we could start banning anonymous accounts and/or new accounts from that discussion, though it doesn't seem very appealing.