Triggers and Mantis shrimp kill fish in different ways. Just because they can kill other fish, doesn't mean that they can't defend themselves with that means. Triggers obivously use their mouths and mantis either spe@r, or grab and smash. A larger aggressive Trigger will grab and rip pieces of the mantis off one by one if he can't get him in one shot. If the mantis is large enough, it will grab the trigger and either spe@r or club the trigger to death. The way some clownfish have managed to survive being housed with mantis shrimp is avoidence. They know to stay away from a smasher mantis, who probably isn't too interested in a clownfish anyways.
Have you ever seen a zoo exhibit, where they lions and tigers together? Or lions and alligators? They are capable of defending themselves, but they eventually kill each other. Of course you could point out some random scenerio where some tiger club was raised with a lion or dog or something, but of course there's always an exception to every rule.
FWIW with a 65gal, I would stick to a reef, with smaller fish. IIRC 65's are 3' long? Not suitable for tangs, and I certainly wouldn't recommend keeping multiple triggers in there. You could house a smaller Humu or another small Rhinecanthus for a bit, before they outgrow the tank. But you'll be quite limited on other fish to put in there.
