Were I seller, I would completely appreciate your perspective and would have the same exact concerns for the obvious reasons:
...but as a buyer I'd never buy a bike without testriding it. So I'm not sure how one finds the right balance if you're selling it privately. Seems like you need to either find that one-in-a-million buyer that will buy it unridden, bite the bullet and let them take it out, or sell it to a dealer at a loss. I'd suggest the second, and have them sign and date a clearly defined rider agreement that says if they crash it they bought it.