Huh. When you are defeated, they do re-spawn, no matter how quickly you get back.
Re-spawning means reappearing after they're defeated.
I believe the term "respawn" is out of context. To me, the cheat ability of Skurkis in the final dungeon of Azteca is the correct term of "respawning." She can keep bringing back her storm minion over and over again in the same duel (without defeat). Lyon Lorestriker is another example with his Myth minions.
Minions resetting with a boss after a defeat, happens quite frequently and isn't unique (some minions do and others don't). Getting defeated and reseting a dungeon will always make a minion return with a boss.
I believe the majority of the "no" responders to your thread had a different interpretation of "respawn" than you did.
None of the MMO/urban dictionaries I could find clarified the term beyond simply....re-entering the game at a designated location on a map. Maybe someone in the community has a better way to distinguish between the two scenarios.