Naivete will get you hurt--but being polite and respectful is not the same as being naive. If there's one thing I have seen hurt Aspies more than anything else, it's the way some will embrace hatred and come to believe that the world is against them. It's not just that they can't see the good in the world, though they usually can't; the worst of it is that they lose hope that anything can ever become better.
A person simply cannot be happy if they see the world as unvaryingly hostile, and then either hide away in loneliness or to attack in pre-emptive hostility. This response to the risk of being victimized will hurt you much more than it protects you.
Unfortunately, the only solution is to learn to risk being hurt, to face the danger and the pain squarely and realize that the opportunity to make the world better is worth the price.
Sometimes people hurt us. Sometimes people even kill us. That is the truth. We cannot be absolutely safe. It is better to respond with acceptance, to refuse to hate, to help each other and protect each other. Remember that there are people much more vulnerable than we are; those people need us to protect them while they grow up, or get back up after having been beaten down, or find a way to make people listen. One day they may protect us in turn. I'm not just talking about other autistic people here, either. People in general--people who are young, or old, poor, unpopular, whatever. The more you learn to love others, the more your fear of being hurt will fade.
This is not some kind of long-faced martyrdom thing, either. It's not going to make you feel depressed and scared and victimized. In fact, the opposite--To be able to hope, to love, to help, even when things are bad, makes you feel very, very powerful.