Our society is not without faults. Our domestic and foreign policies are also often flawed. To correct failings, we need people who point them out, however unpopular that may be. We should be enabling a wide framework of public discourse, not seeking to silence people. To date, we haven’t quite reached the level of hysteria of 1950s McCarthyism, but we are perhaps coming close.
No, extreme is the further away an ideology is from centrist/moderate ideologies. At one end of the spectrum is fascism, at the other is communism.
And who gets to dictate what defines a centrist or moderate ideology?