I wonder if they think that by having the sign-off stop at the CO level, they are somehow reducing liability for the borg? I don't see that being the case at all because COs are full time employees (the branch directs their activity and provides financial support) and are still agents of the WTS.
Now, if they moved the appointment to stop with the BOEs, that would likely break the agency relationship or at least make a good arguement since the branch wouldn't have as much control.
I think that's why they stopped having the branch sign off on pioneers because they were afraid that someone would be able to make the arguement that they are agents of the WTS since they were appointed directly by the branch. Now, the BOEs appoint/delete pioneers and just inform the branch.
It's really difficult for a high control religion to give up any control. So on the one side, you have the cult masters (GB) wanting to run every aspect of their members lives and on the other hand, you have the legal department attempting to reduce liability and protect company assets.
Let's see who wins the arguement. I'll bet if they get a few more multi-million dollar judgements, the lawyers will win.