The Nighthawk who was a Defenders member was from Squadron Sinister, not Squadron Supreme. Squadron Sinister was introduced first by Roy Thomas as an parallel universe evil version of JLA, and later on he decided to create a heroic parallel universe version of them called Squadron Supreme. But Squadron Supreme mostly stayed in their universe (until it was destroyed), while the evil Nighthawk stayed in ours, reformed and joined the Defenders. He actually died before the Squadron Supreme Nighthawk, who impersonated him for a short while. I can't blame anyone for getting confused by all this.
― Tuomas, Wednesday, 1 April 2020 09:11 (four years ago) link