I'm not an expert and not sure about these issues, but isn't it a good argument that boycots might not be effective because it'll give others the impression that somebody is being censored and it might rile people up? I hate types as Carlson, but his fanbase and some people on the fence will see a boycot as an attempt to put him down because he's telling the truth. Also when you start supporting boycots you begin to normalise these kind of actions so it will be easier in the future for governments and companies (which are increasingly growing and are much less democratic than governments) to cut off people and voices they don't like. Please don't accuse of being a Nazi or a liberal as some people like to do here when somebody disagrees but I think there might be something in oppossing boycots.