Brandon Marshall was not the same player on the field last year.  His production and impact plays dipped (maybe it was the injuries, maybe it was all the backlash).  Marshall is getting paid millions of dollars to make plays on the field.  He should be thinking about plays that he should make to help the team win....not about making political statements.
Players can choose what they want to do.  They also have to live with the consequences (like Kapernick is realizing now).  All I am saying is that Brandon Marshall better be an impact player on the field.  Especially when he is bringing attention to himself and the team if he chooses to kneel.  If his production on the field is sub par or average, any NFL team will be quick to cut him (as the attention he brings does not justify his production on the field). 
Just my opinion.