If you genuinely think a dictionary has a better understanding of protests than Martin Luther King Jr, you either don't know his history or are not being serious
Got it, so all the protests for US labor laws, for the end of segregation, and for the end to Apartheid South Africa are all not protests by your definition. Because they interfered with the flow of other's lives.
I strongly suggest you read any of the works of MLK Jr or his autobiography. Because you fundamentally misunderstand the point of nonviolent protests against injustice
Of course they can. Dictionaries are not the Bible. They exist to describe how words are used, not how they should be used. Words' meaning changes over time ("gay" meant "happy" in the 20th century, to use the tired example) and new words get added to the dictionary every day (most dictionary websites have little blurbs showing words they've recently added). Dictionaries have historically, and continue to, change in response to how people use words, not the other way around. If your entire argument rests on the dictionary definition of the word "protest" not explicitly mentioning that to be considered a protest, something must be disruptive, it's not a very good argument.
It also fails to consider that methods of convincing people who would rather simply ignore the issue to care about it that are not disruptive are few and far between.