on odesk, pay nothing and still leave feedback?

why the hell does odesk have this policy
if employer pays nothing, he cant leave rating.
well i hired this guy and waited and waited and he didnt deliver anything.
so i need to end the contract, pay nothing, and leave 1 star. but i cant.
what the hell?

yeah odesk has some logic flaws in their system...i literally just had the same situation but got fleeced into paying an upfront payment :-(