I'd think that an organization could establish rules for grading and selecting timber for various applications, offer training that is structured and can be shown will assure uniform testing and certification of it's inspectors. Then it's a matter of getting recognized and accepted from state to state. After all, states want to assure the safety in their building codes. Make the standards of the organization surpass current standards or be tailored more specifically to timberframes. Now, how to prevent money from becoming an issue? Of course an inspector needs to be paid for their time... but how do we prevent it from becoming like the other grading org? How can it stay open to anyone wanting to learn and pass certification? The point is to allow anyone to do this so that they can grade their own stuff, and their buddies stuff. Another question is, are graders subject to liability in the event of a failure of a timber?
As an grader, would you need to keep a log of every timber graded? Numbering that timber and documenting it's defects and grade score? Does he need to supply rules for use of the timber in a frame, like a document that specifies keeping knots of a certain size out of the tennon or mortise or critical shear area?
All things to think about.