Do you really think that the KKK actually swung the vote for trump specifically? He won by a huge margin, especially among...people that don't normally vote in elections, and those that despise the big government of the republican party (i.e. jeb bush or chris christie). The leaders in every poll every step of the way were the tea party candidates. Whether or not a few thousand KKK members would be hypothetically locked up would not have changed the result. And on your second point: there's plenty of ideologies that have been put into practice and had disastrous consequences. Like...soviet communism for one. What about atomic or chemical weapons? They've caused some serious harm. Should we make it illegal to support nuclear weapons?