Methinks, Hanuman was not cognisant of his own prowess then? And therefore he did stood to witness the miseries of Sugrīva— the king of monkeys who was dearer than his life.
नहि वेदितवान्मन्ये हनूमानात्मनो बलम्। यदृष्टवाञ्जीवितेष्टं क्लिश्यन्तं वानराधिपम्॥