Here is an attempt to summarise the main points being made...
The initial question is, would life in general be better if all humans under 120IQ vanished overnight.
Nearly everyone here will agree that the answer to this is yes, the cause of disagreement is how we should respond to this 'revelation'. The most obvious response is, kill 'em all. The objections to this are as follows...
a) The plan will be almost impossible to implement, gaining and maintaining the amount of power required to carry such a plan through is unrealistic.
b) That the supporters of this plan have underestimated the psychological impact of such an event. I want to expand on this, although what I say here will likely be considered pseudo-esoteric nonsense. I have no objection to mass killing in the form of war, which is natural to man, however, enslaving man to a mechanical process of execution in the ways that are being suggested will most probably trigger some sort of psychological instability. In my opinion, the machine already possesses too much power, it is too far beyond the control of its maker, to industrialize the slaughter of billions may have vast and unforeseen consequences, though I cannot really predict what they will be. It seems silly to think that one could return to a more natural way of living through such unnatural means.
c) There are more realistic ways of achieving the same result. I have already made suggestions in this direction.
Having considered these points I believe the suggestion that we should promote the holocaust of those under 120IQ to be an absurd. This type of emotionally driven symbolism should be abandoned and replaced with real ideas, plans etc.