Civil disobedience is a crime also. MLK and Gandhi were criminals.
First: Their illegality is arguable. When civil rights leaders engage in actions like sit-ins, the authorities often try to stop them on three grounds:
By invoking statutes that are overbroad and loosely defined, like “disrupting the public order”;
By invoking statutes that are petty and tangential, like exceeding the capacity of a building in violation of a fire code, or characterizing the distribution of leaflets as littering; or
By taking proactive measures that exceed their own authority, like issuing injunctions against protesting (which was the basis for MLK’s arrest).
All three of these grounds are legally questionable, or outright specious. And more importantly, all three have to be weighed against the protestors’ First Amendment rights, which traditionally have very strong power in these situations. (I don’t have much faith in our current Court to support it, since it is uncharacteristically insensitive to individuals’ rights and deferential to authority - but its tone is an anomaly in the history of the Supreme Court.)
Second: Even if civil disobedience can be legally prosecuted, it is not culturally considered a crime. Most people will be reluctant to call it morally wrong or illegal, even if they don’t support the cause. Contrast this with serious vandalism or violence, which are not just illegal but reprehensible.