I'm confident that all of these little exploits will be identified and worked out in time. The entire community has a vested interest in doing so. This is an example of the wrinkles being ironed it in action.
I'm honestly surprised that there isn't more exploitation given the relative complexity of this system, but it seems quite airtight in my mind (except for this one, imo)
Look forward to seeing @ned and @dan responses... I'm sure they're already working on it anyway..