Is this the best way to prevent someone fucking up the protocol? If someone did, many would be locked. The first to hit the end of their lock times would get out first. Somone who borrowed the YFI to fuck with the protocol would have an easier time paying back the loan if the value drops.
Edit: I will add that giving YFI holders choice may encourage more YFI to be staked in governance, which has its own benefits, including making it more difficult to mess with the protocol.