To be peaceful one needs to be a pacifist. An activist is one who stands up and fights for what he/she believes in, the keyword being fights... so to be a peaceful fighter is like trying to be a sweet lemon, you are either sweet or lemony, you cant be both at the same time...
If this group at least dubbed themselves as "activists" rather than "peaceful activists" then it would make a little more sense and allow me to sleep a little better at night knowing that at least they were slightly intelligent people that werent trying to fool anyone into thinking their intentions were entirely peaceful...
The only true "peaceful activists" that ever existed were the Buddhist monks who burnt themselves alive to prove a point but they didnt harm anyone in the process...