Just a thought here regarding defensive weaponry and sighting options, bearing in mind the opinion is coming from someone (me) who grew up reading the likes of Jim Wilson, Masad Ayoob, Elmer Kieth, Ed McGivern, and others.
If you are carrying a weapon for personal defense you should be able to hit a target at a defensive range of distance without the use of the sights. Using your weapon should be second nature and feel as an extension of your arms. When I am practicing with one of my defense guns, I don't even notice the sights. And I consider a pistol as a tool to fight my way back to a proper weapon, my rifle. Said rifle being my Marlin 336. With the Marlin I hit a 6" plate at 50 yards consistently without the rear sight attached. With my 12 Guage I shoot trap and do not have time to sight the gun. I point and it busts clays.
If you have a threat and it's bearing down on you from 50 yards you have precious few seconds to react and fiddle f***ing with sights is too costly. This of course is my humble opinion, never having to use a weapon in self defense.
All that being said, when I am shooting silhouette out to 300 yards with the Marlin, it's sporting a 4x Redfield. Sometimes accuracy is important.
I haven't been in griz country, but I have spent a fair amount of time in black bear territory. Fifty yards is like the maximum distance when thinking of self-defense against critters. The only time in the woods where you'll be seeing fifty yards around you is if you're in a field, spread-out trees, low-lying brush, or on a trail or road.
I hiked up Mt. Moosilaukee via the Carriage Road Trail back in 2018. The Carriage Road Trail is, as the name suggests, an old road that horse-drawn carriages used in the 19th Century to bring tourists to a hotel that existed on the mountain and is thus wide and flat. Early on the hike, when the trail was pretty flat and you could see down it a fair ways, I saw a black bear cub in the trail. The cub was facing the opposite direction and eventually walked up the trail and went off into the woods. The cub was probably thirty to sixty yards away. Put it this way, out of normal pistol range.
I'd say that situation isn't typical for two reasons. One, I was on a particularly flat, wide, and clear trail that isn't typical in bear country. Two, grizzlies charge, black bears don't normally.
Fifteen yards away:
Expect the Unexpected: When Grizzly Bears Charge
This is probably ten to fifteen yards away, go to 0:32-0:35:
This one is pretty far away:
It's Better to Shoot a Charging Grizzly Bear With Your Gun Than Your Phone
So ten to fifty yards seems typical for griz charges and attacks.
That all being said, I agree that sights are superfluous in a "Its heading right for us!" situation, but a modern red dot is going to be low enough and small enough and mounted hopefully properly so you can achieve co-witness with the iron sights. So in the precise event of shouldering a rifle or shotgun with sights, and there isn't any dot, you can still see the front sight. Personally, I wouldn't have any problem putting a red dot on a .45-70 lever action for use in griz country. I would just make very sure to remember to change the batteries when needed and to see what happens when I shoot with irons and the dot off and mounted. If anything, a griz charge is probably one of the situations where a red dot would be great because the dot is right there in the middle of the optic and the bear is going to be big enough of a target. Its a bear, not like shooting a clay pigeon with a rifle at 100 yards. That's a big target.
