If you have a round in the Glock chamber (which normally gets there by virtue of the slide stripping a round out of the magazine) and rounds in all chambers of a revolver, then pulling the trigger on either firearm will result in a bang. Any belief in “safe action” beyond that point requires too many fairy tale best wishes for my comfort. I have, and use, Glocks, but Mr. Glock isn’t going to be there to comfort my family if I rely too much on his marketing abilities.
Going back to the original story, my guess is that somehow the Glock trigger was pulled.
Activating the trigger on a Glock is easier than the trigger on a double-action revolver.
Just here in the FR archive, there are numerous recorded incidents of Glock mishandling negligent discharges that would not likely happen with a double-action revolver and would never happen with an Hk P7 automatic.
A Glock is mechanically engineered to not be able to be a confidently prevented from accidental/negligent discharge as other competing designs with features such as grip safeties and DA/SA trigger operation.
Those who carry Glocks for CCW need to honestly understand they're carrying a cocked single-action pistol. The Glock was intended as a military sidearm using a military holster, not a dedicated CCW piece like a S&W Model 36 or a Colt Detective Special.
I often carry a Glock 19.