A good way to get through to someone that doesn't understand the concept of armed self defense is to ask them a simple question.
Who owns you?
What?, nobody "owns" me.
So you are free to do what you want to do?
Yes of course.
I agree we are free to do what we want (within the law of course), but what if someone else decides they are going to make you do what they want?
I would tell them no.
Ok, but what if they are determined to control you and use force to do so, then what? Unless you are willing to fight for your freedom, then now they own you. Shouldn't you be able to defend yourself against such people?
Yes, but....
No buts about it. You have an absolute right to defend yourself, and limits on that right as to what tools you can use to fight with or what you should have to do before you can fight are immoral. Those restrictions only favor the person(s) wishing to enslave you.
Anyone that doesn't understand this simple truth is not fit to be in any position of power.