I'm sure it's possible to bend them... but I've cranked on mine fairly hard, and so far so good (knock on wood). It's my understanding the bent clamps were defective to begin with... not a result of over tightening. But I'm guessing you can, so if you get a knife that won't stay locked in position... I wouldn't get carried away... I'd use some of the other tips, like a piece of tape or leather to help hold it.
I also found a drop of oil on the bottom screw makes it easier to snug it up without having to apply a lot of force.