John's Gospel has already used absolute ego eimi sayings with possible echoes of Isaiah's divine self-identification.
Isaiah 43:10 is the most relevant theological background.
The falling response and John's larger 'I am' pattern make the scene suggestive of revealed majesty, but the divine-name reading is not grammatically required.
For that reason the record is retained as Supporting rather than made to carry independent proof of deity.
The arresting party draws backward and falls to the ground.