antinatalism and pessimism

What is ridiculous about it? There's no mandate that mankind are fulfilling by existing here, and it's generally considered a bad thing to take dangerous gambles with someone else's wellbeing if you have not obtained their prior consent (even if consent cannot be obtained).

If you want to point out any nonsense or fallacies (in layman's terms, preferably), I'm very confident that I can address them. Suffering is an objectively bad thing, by the definition of the word (if that's what you're hinting at with regards to antinatalists being 'ethical objectivists') and therefore there needs to be a compelling reason to justify inflicting it on someone (usually this would be something like self defence).