It's impossible to prove that Hawaii wouldn't be attacked without military presence. Historically the only two nations who (AFAIK) attacked it without a conventional military presence are Tahiti and the United States.
On the other hand that same military presence also makes it a target-rich environment. If you were another hostile Pacific rim power you can't afford to NOT attack. There's no denying probabilities of hostile action go way up. 1941 for example.
But then there's the case of Switzerland. They seem to sit out all the wars despite holding lots of desirable treasure and territory. If Hawaii was to position itself as the Swiss of the Pacific with a strong militia/people's army but a clear mandate to take no sides in international conflict then we'd likely be in a much safer position than we are now.
Argentina attacked unarmed Falklands.
If Hawaii wasn't part of the USA, e.g. Kingdom of Hawaii instead, then The 2nd Amendment wouldn't be relevant in Hawaii, and Kingdoms usually aren't fond of armed peasants. and then this website wouldn't be.
separately, seriously, missile interceptors are forward deployed, and operational. I doubt any North Korean land-launched armed missile would ever hit Hawaii, or even Japan. The Israeli's have deployed their "Iron Dome" system, maybe only 90% effective, but that's because they don't bother shooting down the palestinian rockets that are going into farm pastures or wastelands. now, submarine-launched nuke is a different story. and you can count on one hand (maybe) which countries have that capability, and NK isn't one of them.
somebody chose not to shoot down the missiles flying over Japan, perhaps to better evaluate the capabilities of the threat. and they knew it wasn't armed.