I was kind of thinking the same thing.
This is true.
I don't think there was enough information given to determine whether or not the submissive was wrong to refuse. Even a slave has the right to veto anything that might harm her.
Generally, I agree. However, I have to wonder what control a Master has if punishment is able to be controlled by the slave with the use of a safe word. Punishment isn't the same as play and isn't meant to be enjoyed.
Why? I would think that anyone entering into this type of relationship would know each other well enough to be sure of what they're getting into.