What were all those "whites only" lunch counter sit-ins MLK did then? They sound like a textbook definition of "provoking the very people you are trying to convince", and yet.
While at a high enough level of disruption, the acts of protesters might harm public support of the cause, I think that level is probably pretty high and supporters will largely understand if they are temporarily inconvenienced, while some people who already oppose the protestor's cause will tend to use any inconvenience as a more socially acceptable excuse to justify their opposition instead of more honest reasons like plain old bigotry.
Pissing people off (too much) seems to be counter-productive and can prevent people with sympathizing/empathizing/joining you:
> For more than a century, from 1900 to 2006, campaigns of nonviolent resistance were more than twice as effective as their violent counterparts in achieving their stated goals. By attracting impressive support from citizens, whose activism takes the form of protests, boycotts, civil disobedience, and other forms of nonviolent noncooperation, these efforts help separate regimes from their main sources of power and produce remarkable results, even in Iran, Burma, the Philippines, and the Palestinian Territories.
* https://www.goodreads.com/book/show/10056014-why-civil-resis...
Laws buttress/codify the current social order, and forbid shaking it up, in particular through disruptive protest. If the social order is racist, then these laws will be used to preserve racism. They're inherently repressive, not inherently racist.
If you're the government - you don't want to abandon them. If you're a social movement - you're against their existence (if you're more principled), or against their enforcement in your case (if you're more opportunistic).
That's a very convenient "if". I just declare social order is racist, so the laws no longer apply to me and any lawless action I take instead of being a crime becomes struggle against racism. Nice deal. Except the society that allows such deals can not survive. Of course, if you want to destroy the society - either because you genuinely think it's "racist" or because you just don't care - then you don't have a valid base for complaint when the society tries to defend itself and arrests you. You are literally destroying it, what else should it do?