To defend hibernation/shutdown: if I lose my laptop or it is stolen, and I realize I will never see it again, then at least I will have peace of mind that no one can ever recover the data, assuming I had a strong password.
An evil maid attack assumes I will have the laptop in my possession again. This is a different problem, and requires different measures to defend against. I'm interested in hearing why you think leaving a laptop in sleep mode protects it from an evil maid attack.