You can ask someone to stop doing something legal. I'd hate to live in the sort of world where you can't. HN moderators would send the police after you to seize your laptop if you make bad comments. The only way to get your roommate to stop eating your plums would be to charge them with larceny. Every relationship would end with a restraining order, or it wouldn't be over. Failing to turn in a homework assignment on time would lead to a court date. Buying more than ten items in the express lane would get you arrested for fraud.
If that isn't the world you want to live in, let's get rid of this idea that just because I have no interest in the government stopping you from doing a thing by threatening violence (and that's all a license is - a statement that the following activities are not copyright infringement), I'm totally fine with you doing the thing.