To me it is blocking expression that presents no plausible harm to anyone. Yelling fire in a crowd to start a panic, making a specific threat, and intentionally spreading lies as to defame all strike me as harmful language and should be curtailed somehow. All expression of any kind not plausibly causing harm should be allowed and equal in the market of ideas despite my personal opinion of them which is a bitter pill to swallow when neonazis appear all to common. The is my opinion.