Thank you, Takata. The lower belt only for the PNF is easily explained as the shoulder harnesses are never used during cruise. The "no seat belt" for the PF requires greater explanation. At some point it went from fastened to unfastened. That requires that in the recovery from the sea bottom the buckles for the lap belt were undamaged and were not fastened. If they were not fastened as recovered, then either the PF unbuckled at some point or the belt was unbuckled in the impact. Without closer examination one cannot judge which is more likely.
Understand the captain was standing...I now recall that his body was found and that he was standing made sense at the time, as it does now.