After Selim Pasha finished introducing himself, Marshal Saint Arno and Commander Lagren immediately realized the reason Selim was appointed as the leader of the Ottoman Empire's divisional forces: most likely, His Majesty the Sultan of Constantinople feared Omar Pasha's immediate surrender, which led to his son's appointment to command the Ottoman Empire's support troops.
If Saint Arno and Lagren's guess was correct, the real commander appointed by the Ottoman Empire was not this somewhat foolish-looking young man before them, but most likely Omar Pasha in Silistra Fortress.