There is nothing about that statement that is remotely correct from a legal standpoint, though I understand your frustration.
An annual is no protection, but at least you make some more money off of it. The best way to protect yourself on a pre-buy is to have an agreed upon scope of the inspection and an indemnity agreement. The latter should hold up in most courts, but likely would not for an annual inspection.
Or, as home inspectors often do, put a limitation of liability clause limiting the liability to the cost of the inspection.