I believe that they are doing it this way because PBLS fears losing control to their new "partners." Plus, the new partners want to be certain that PBLS is going to be cooperative in the new relationship.
One I have been asking myself. The only reasonable answer is that management wants to raise the PPS. It could be that the Series III may not be enough of a poison pill. Management may need the Longs, and may need them to hold as stubbornly as they have in the past. Therefore the reward/incentive to hold. JMHO