If a low reputation user posts a question about the Holocaust, rather than being immediately posted, it should receive a notification telling the user that the question will remain visible (and editable) by that user, but will not be published until it’s approved by either the community or a diamond moderator.
The question should remain invisible even if the user edits it. That way, users won’t be able to circumvent the filter once it’s been triggered. In addition, users won’t receive any warning before the question is submitted. This will avoid people trying to misspell the word to circumvent the filter.
Update: I had a look at a sample of questions, based on which ones I flagged. It looks like a sizeable proportion lasted longer than 2 hours (if you define it as precisely 120 minutes). While the questions I flag may be a biased sample (for example, I can only flag questions which haven't already been deleted, and I'm more likely to flag questions which were posted when Australians are awake), I think that "virtually all ... within 2 hours" is an exaggeration.
Less than 120 minutes: https://skeptics.stackexchange.com/questions/43439 https://skeptics.stackexchange.com/questions/38788 https://skeptics.stackexchange.com/questions/38322 https://skeptics.stackexchange.com/questions/38264 https://skeptics.stackexchange.com/questions/36478
More than 120 minutes: https://skeptics.stackexchange.com/questions/42754 https://skeptics.stackexchange.com/questions/39608 https://skeptics.stackexchange.com/questions/38317 https://skeptics.stackexchange.com/questions/36450 https://skeptics.stackexchange.com/questions/36336 https://skeptics.stackexchange.com/questions/36245 https://skeptics.stackexchange.com/questions/36103