If we eat it, it's food. That includes the plants these protesters consume. Just because their victims don't bleed or scream, doesn't mean they do not suffer in any fashion. They just lack the means to express it. I doubt any life form appreciates sharp implements being used to dismember it, being plunged into sub freezing temperatures, cut off from it's air supply (or even subjected to Air Supply), or otherwise having its life snuffed out. Nor does any life form care whether the attack on its life comes at the hands of a human, the claws of an eagle or lion, or the teeth of a rabbit. They need to re-watch lion King and pay closer attention to that Circle of Life discussion Mufasa gave.