Yes, there was a handgun present. It was never used because the only person who had access to it did not know how to use it. Very likely they would have had the same problem with bear spray.
We have a couple of minor misallignments in our memory. The pistol was in a pack, as I recall. The bear spray distances are from the Tom Smith study. Aerosol movement in air is a complex, dynamic process. (I have an engineering degree and a meteorology degree) Smith used a complex computer program to simulate the wind effects. I am not a big fan of using simulation programs, but it only makes sense wind would have a big effect on a quickly aerosolized spray cloud.
There have been several incidents where people said they could not use spray because it would be ineffective because of wind, (only anecdotal information). There is at least one documented case where it was ineffective because of cold.
Smith is a bear spray proponent, so when he publishes a paper saying wind significantly decreases the range, I paid attention. He also said it would not be a problem, in an interview, saying just wait until the bear is within 2 meters to spray! ( I found that to be silly). 1 meter/sec is about 2.24 miles per hour.
Glock pistols do not have traditional safeties. The pistol did not have a round in the chamber. If you know what you are doing, and practice, that is not a big problem. If you do not know what you are doing, and have not practiced, getting the safety off a bear spray can is a big problem, too.
I recall reading the official report. As I recall the bears had bear spray on them.
I read these reports with a critical eye. They seem to attempt to convince people bear spray is extremely effective. They appear to me to be written by people who want to believe such, because they are extremely concerned about saving bears.
I may have been the first person who made it widely public that Uptain had sprayed the bears before he died. As I recall, the official report was not published very widely.
Maybe Uptain carried the empty cannister, clinging to it as he attempted to get away from the bears. Maybe he was given a mortal wound before he was able to spray. None the less he died using bear spray.
If Uptain had fired a handgun while defending against the bears, I would have scored it as a handgun failure. It is useful to reverse the methods and apply the same logic to each. In the first and most commonly referenced bear spray study, Tom Smith and Stephen Herrero only included instances where bear spray was sprayed against bears. Many of the cases were park personnel harassing problem bears.
In their firearms study, the included all instances where a firearm was present and someone tried to use it. The looked hard for cases where people were injured. So the Uptain case would have been both a bear spray and a handgun failure in their studies, even though the handgun was not fired.
They admit, in the firearm paper, they have a problem with selection bias about firearms. Admitting it made the publication valid. The bias is seldom discussed.
Here is the image from the Tom Smith paper on Bear Spray.

Claiming this was a "bear spray failure" is tortuous logic. I can see how you could choose criterion that would lead to this result, but that makes the criteria itself problematic for anyone trying to get a handle on this subject. The victim made a choice not to use it, and was then fatally mauled prior to any use per the eyewitness/survivor. Speculating that the victim used it and then carried it to his final location doesn't change the testimony and forensic evidence that the initial mauling of Uptain's head was mortal. Nor does it change the fact that it drove off the bears who could have feasted at their leisure after everyone was dead/gone. I call that evidence of a win - you just need to deploy before being mauled.
Pulling a tab on bear spray is a simple as it gets. (My problem is that it comes out too easily when bushwhacking - all my cans are now lacking their safeties, and the replacement cost is exorbitant for little pieces of plastic. I've learned to be careful.)
I don't care about saving bears, and am pro-2A (including private ownership of AA, anti-tank and other advanced weaponry in the spirit of the 2A). The victim's brother was an acquaintance of mine (volunteered and traveled with our teams several times when I was ops manager at my last job.) I see irrational bias and insecurity motivating the denigration of bear spray, and a pointless focus on presumed "save the bears" motivation that is really beside the key point of keeping people safe.
I simply can't buy those charts and have to wonder if something is misprinted. 1 meter/second is just over 2 MPH. Since when is the wind in Wyoming ever that low?? Yet this would have me believing that bear spray can virtually never be used in Wyoming, and just strikes me as utterly unreal.