“The Koch brothers are libertarians and liberals rightfully recognize them as an arch enemy.”
Both are for open borders and amnesties. Koch brothers are well know to be one of the GOP big donors who push Boehner and Cantor towards amnesty
Amnesty will kill the right wing in America. Libertarians too. Third world immigrants are not libertarians
But no one would say the Koch brothers are liberals. Immigration is a good example of how libertarians can arrive at the same position as liberals by opposite logic. For libertarians it’s a limited-government issue, not a social justice issue. They also favor the total dismantling of the welfare state and all social programs, which is the only context in which open borders could work, at least in theory. Of course the former will never happen which makes supporting the latter a bad idea, but it shows that they’re coming from a different place than liberals.