Google has a policy about "sensitive and disparaging terms associated with named individuals" in autocomplete https://support.google.com/websearch/answer/7368877?hl=en which is often why you sometimes may not see the queries in autocomplete that you expect. It also has a policy about "violent or gory predictions" so it wouldn't surprise me if you aren't seeing autocomplete suggesting the Christchurch video, if that's what you mean.