In a way, Trump has disrupted the whole so called 'protests'. He has derailed it now, like a train wreck on two important levels.
First, the goal of the protest has been usurped. The original goal of the thing was supposed to be a stand against perceived 'injustice' against the poor little innocent American Black man. Well, that is now gone. Now, the protest will be seen as a protest against the racist 'white-supremacist' nation of the United States of America, but not for supposedly oppressing Blacks which was the original goal. Now it will be seen as a protest against America and Americans for electing Donald Trump as President. Trump has successfully made the protests about him, rather than the Black Power, BLM, Black Panther, Black Supremacist, movement for which it was intended to be.
Second, if everyone kneels, then nobody does. What I mean is if everyone 'takes a knee' then the whole thing sort of loses impact. It is no longer a protest in support of the Black grievance culture. In the case of everyone doing it, Black, White, Latino, etc., then it is just a general protest about nothing, really. It then becomes just a general protest against President Trump and the nation which elected him. All the original Black grievance stuff gets lost in the fog. This is why some BLM gatherings banned all White people no matter who they were. Because they didn't want Black and White people to be seen together because this would hurt their message of hate and oppression.
If nothing else, Trump has trivialized the thing and has made it about him. He has thrown a wrench into the machine and really has changed the fundamental nature of the protests. From now on, I think many Americans will simply see it as just another anti-Trump stunt, which completely obfuscates the original message.
If there is one thing Trump is known for, it is being able to change the rules and the perception of a problem. And I think in this case, he has done it again.