Learning to compete against others in a different use than the attempt to injure somebody with the weapon, yes. Just like learning to play baseball makes what is otherwise a far more deadly weapon "useful".
This is solely cosmetic, there are better weapons, more deadly ones, that are not being banned solely because these are flashy. It makes no sense to ban these, but not a staff, to ban these but not ban carrying a simple stick.
There is no real rational basis, this weapon is no more deadly than using a broom handle to hit somebody, or grabbing a bicycle lock. In fact people who own nunchucks usually are people who are learning in a class environment and who also learn things like control and discipline, in most cases it is beneficial rather than a danger to society.
And I'm not arguing about her ruling. I'm arguing against silly irrational laws whichever the source.
And I think it is funny how much you personally attempt to attack me by using inane phrases like, "People like you". When you generalize that way you are almost always off target when dealing with an individual.