You're maybe one of the people they're trying to reach. If so, thoughts along the lines of "I don't like this behavior" might be helpful for the people working to strategize in the movement. Responding to a protest with "I don't think this will be effective in convincing people" says one of a few things:

1. "I agree with some of the goals of the movement on the surface, but I would rather start a conversation about civility than about the actual problems they're trying to bring attention to"
2. "I disagree with their goals and I would rather shift the conversation to be about civility than to have to defend my position"
3. "I'm apathetic to their goals and I don't like being inconvenienced, so all I care about is how civil they are being"

Every one of these is an attempt to derail the conversation due to emotions ranging from discomfort to malice, and none of them are worth engaging in.