If those actors really thought what they did was bad they would be trying to revert the outcomes of their actions. Do you see the US moving non-native descendants out of vast swaths of American to set up native-american countries, or paying native survivors the fair land value of all the lands they were driven from? Talk is cheap, watch the hands.
Kent State was barely 50 years though, and sending Predator Drones after anyone suspected to even tangentially be related to terrorism is current policy.
If the US still had an ethnic minority that lived predominately in one area and has been active in terrorism and islamist extremism, I don't think they'd handle it gracefully. Abu Ghraib gives us an idea about what the US would do in a similar situation and it's not been that long.