The bourgeois have lead the recent liberal/democratic revolutions and currently hold great wealth and influence the world, but if we continue along the path of dissolution, eventually even the bourgeois will be eliminated on the road to a total rule of the masses. The bourgeois are supporting this dissolution even though they are unaware of where it leads (i.e. "tools").
Conversationalist appears to be seeking to eliminate this possibility by materially removing the lower elements of humanity. This would prevent further dissolution and probably save humanity from self-destruction.
Most people appear to agree that less stupid people is good. However, the main arguments against Conversationalist's proposition appear to be:
1) Uncertainty - Are we missing something?
2) Improbability - Would such a thing even be possible?
3) Morality - Is killing wrong?
4) Fear - What if I am too stupid to meet this threshold?
In regards to uncertainty - I agree. Is there a spiritual element this overlooks?
In regards to improbability - I agree. Recent history shows societies focused on genocide implode. However, world leaders might be able to achieve a consensus on the issue out of mere self-preservation and pursue some similar plan. The world leaders would have to hold real power though, and not merely the power dependent on support from the masses.
In regards to morality & fear - the philosophical metalhead/nihilist answer would be "death is part of life" and not bad in itself. You could examine what is really "good" and "bad" in this context -
a) Present path: Temporarily increase the number of useless people, burn all resources, turn earth into a toxic waste site.
b) Alternative path: Reduce the number of useless people, use resources wisely, protect earth and improve humanity.