Honest question... Where does the law dictate what the property owner can or can't do on their property? I agree with your opinion, but from what I understand, this law does nothing of the sort.
If you want to prevent people from being able to defend themselves, that is certainly your choice on private property. However, when the eutopia crumbles away and people are hurt because of it, you should accept the responsibility of your actions.
When you open your property to public access, there are laws that you must abide.