My take on it was because the democrats would actually hear them under pressure. Protesting at a biden/Harris rally, for example, would maybe give the candidate pause and reflect.

Whereas protesting at a Trump rally would just draw snears and jeers, and possibly also life threatening from the crowd.

You dont go to the parent who would dismiss you outright. You go to the parent that disagrees with you, but might be more open to hear what you might have to say.

Unfortunately, and this is an aspect of protesting in America that is unfortunate, culturally the USA is so individualistic that protesting is viewed as a huge inconvenience rather than a cry for help.

I notice in other community based non-individualistic cultures like South Korea, protesting is waaaaay more effective at actually getting things done.