If someone refuses to follow the rule does that make him an outlaw?

Yes, of course.

Would you say he should follow the law?

Not sure why my personal opinion is relevant, but he has the option of following the law or not.

If he doesn't, in what sense is he different from my "I can murder whoever I want" example?

At sufficiently high levels of abstraction he is not different. Once you descend to breathable altitudes, other interesting concepts like "harm" and "autonomy" come into play.