From a practical standpoint, if you don't want something used in a particular way, don't post it on the internet. People will either: A. Not download the item. B. Render the offending image but not post it and possibly offend you. C. Render it and rub it in your face. The fact that most people would fall into A or B shows that most people try in their own way to respect other people's beliefs. Interestingly, I think if Please had been used instead of Must, even a few of the category C folks might feel differently. It's a question of how best to honor one's own beliefs while recognizing and accepting that other people's beliefs will be different. I'm not sure I always know the answer to that.

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken