It is clearly a possibility to interpret Gothmog as a Nazgūl. But he was not intended to be one when his name was given as the one who took command after the fall of the whitchking!
When Tolkien wrote that chapter he envisioned the Nazgūl be fly back to Mordor after the fall of the whitchking. All glimpses of that flight were later removed. (We do not if intentional or by accident.) But he named Gothmog the commander in the field after the fall of the whitchking from the begining. That would mean that at least at that time Tolkien did not take Gothmog as one of the Nazgūl.
Respectfully
Findegil
|