I never would say to not fly 
I would just say to cut a piece of thinner cardboard to take up the missing protector thickness so the screws don't touch.
And try to be careful because that motor has a little less protection now, so it could get bent easier if you hit it on hard ground or possibly need to clean dirt out of it as there is less covering. No biggie, just make some allowance for the missing piece and FLY!
