I think it's usually a bad idea to attribute any broad sentiment to HN as a whole, but if you wanted to make the point that it's a tech industry forum and thus shares (with many counterexamples!) tech industry biases, that's a much more grounded thing to say than that it's a "Silicon Valley" site.

I will say this, though, and it's a wild guess so take it as you will: the median opinion among American tech industry workers about the government of Bolivia is: not, in any way at all, ever once thinking or caring about the government of Bolivia.

I would guess somewhere between 5-15%, but I would be surprised if it was over 10%.