Having 'the leg' does not transfer command, so LHS was still 'Captain' and NOT 'subordinate'.
The first highlighted part is true but the second statement is open to interpretation that day. The captain was on rest down the back, but there was no indication who was now in charge while he slept during his rest period. Of course there may have been a company policy of who becomes in charge when two pilots other than the captain are up front. But it seems the second officer in the RH seat was really running the show as pseudo in command (his leg given to him by the real captain) as PF when everything hit the fan. Quite confusing situation especially as the F/O in the LH seat was so hesitant all the way along to take over. But why was he so uncertain?