Nick,
With a feeder grounded conductor, there is no reason to have the same rule as for branch circuit grounded conductors. If the feeded grounded conductor is lifted you have lost the grounded conductor for the feeder circuit and have created a problem for any multiwire branch circuits fed by that feeder. The same thing happens if there are two terminations as would happen with only one termination. As long as the termination is listed for 2 conductors, I see no code or real problem with making a feeder grounded conductor in that way.
Don(resqcapt19)
