Scott, here's my take on this. If you are purchasing labor from outside the pool of Partners then it seems reasonable to view that as a resource. If you are purchasing that labor in units of time, then it also seems reasonable to view that time as a resource.
However, labor allocation inside the Partner pool works differently and consists of 2 key elements: 1) Lead Links look at all the available Partners and decide who can best fill the roles in their Circle; 2) Partners look at all the roles they are filling and decide how to prioritize their time/attention across all the Accountabilities and Projects of those roles. While doing so, they align to any Strategies that have been defined by the Lead Link(s) of the circle(s) in which their role(s) exist.
If necessary, you could define policies through governance on this "labor allocation" process, as Andrea was suggesting. But this has to be done through governance so it is not something the Lead Link can do alone, and it would also need to be done in a circle that has authority over this process. Given that labor allocation spans all circles, this would need to be done at the GCC level, unless the domain had been delegated.
Interestingly I just noticed that HolacracyOne has defined such a policy in their GCC, the Attention Point System, in which they actually have defined a resource called Attention Points. It seems rather complicated, but apparently there was a need, and I would be very interested to hear how well that is working.