This v1.6 ruling aside. I completely agree with Alliser. RAW, the active player should get to resolve their effect first (the Quickfire in the case of the Hunters being controlled by the Active Player).
The v1.6 ruling should have been accompanied by a supporting errata...
I don't know also if that section was updated from v1.6 to 2021 rules.
But my point still stands, without an "Errata" mention then it would resolve as I posted.
A retreat is roll a d6 die then you may move up to unit's speed + result of the roll then you may pivot and your opponent may pivot. So the enemy's pivot is part of the retreat action. So he pivots before you can trigger quick fire.
Close. A retreat is described more or less as you say but excludes "and your opponent may pivot." The rulebook then says "Additionally, if the enemy unit (or units are now unengaged afterthe Retreat is completed, each of those enemies may immediatelyperform a free pivot."
So the rulebook is very clear that the enemy pivot occurs after the retreat. Again, this was the same in v1.6, and the ruling ended up being that the enemy pivot occurs before the active player's quickfire. And I fully expect the same to occur here. But until that ruling is decreed... RAW... The quickfire does resolve first.
Would I ever stand firm on that in a game? nope.