I just imagine the worst case type of shot, a hostage taker and the only thing I have to hit is the head. At 15-25 yards with a red dot I would have way more confidence that I wouldn't hit the hostage. With chunky Glock iron sights I would be scared to take that shot even though on paper I could reliably hit such a target.
They invented co-witnessing sights for a reason. You can quickly verify by sight if the two types are in alignment.
If the co witnessing view is not aligned, then there's a big question for you. Is it the red dot that's not zeroed or is it the iron sight (bumped it or a screw came loose, etc).
if you trust the iron sights more, then ignore the red dot. if you remember cracking the front sight on the pavement when you fumbled it trying to clear your holster, then maybe neither is accurate.
Maybe you should practice with no sights visible and use a 7-15 yard distance. 15-25 is unrealistic to attempt a headshot with a handgun under pressure.
I guarantee you you'll be able to hit the target where you want without really using the sights. I was doing that in IPSC timed exercises. Pull, point, fire. You were so close, you'd have to really try to miss, or be in such a hurry that the sights won't help anyway.
In Front Sight Defensive Handgun training, we taped the silhouette of the hostage in front of the bad guy's head with just a couple of inches visible around the hostage. I hit all 3 rounds in the right area without touching the hostage. That was at 10', and i don't actually remember taking a time to get a perfect sight picture.
i'm sure the bad guy is going to be patient while you line up the shot that's meant to kill him.