But I think leftists would share the same premise! They would phrase it differently, they’d say something like: “the founders were white men who wanted to limit government power so the government wouldn’t be powerful enough to do things like end slavery or take their property.” But that’s the same argument. The traditional view is a small government of enumerated powers. The post-civil rights view is a powerful federal government that can protect minorities from democracy.
> They won't say they are hostile to the Civil Rights Act and every solution to problems like segregation, oppression of minorities and women, etc. And they don't offer any other solution.
That doesn’t logically follow. The analogous mistaken argument would be saying that those who insist on due process for deportations must support illegal immigration, because “they don’t offer any other solution.” Of course that argument is wrong. Those people simply aren’t willing to compromise on due process to address illegal immigration.
Similarly, you can be unwilling to compromise on federalism and limited government, even if it’s to address oppression of minorities. That doesn’t mean you support such oppression, simply that you prioritize other values more highly.