No, his opinion is invalid because he is a white man thinking that he knows what's best for communities of color. Since he is not an affected member/of a community of color, his opinion on the matter of whether or not protesters (who are mostly people of color) are justified is INVALID. 

You can't know what it's like to be a bear if you are not a bear. Nick is not a person of color, he shouldn't be expressing ANY opinion on whether or not the concerns of people of color are *justified* since he has NO experience to base that opinion on.