TAKtical, any gun that does not have a manual safety and instead uses a "safety" such as a Glocks will be more prone to a Negligent Discharge. Just as one example, if someone is using a poorly fitting holster and inserts their Glock and a piece of leather gets into the trigger guard, the gun will discharge (and yes, it has happened). If the same situation happens with a 1911, the manual safety will keep the trigger from being pulled.
My 4 cents is that you're leaving out the human part of the equation. Anytime you add more events and options to a procedure, you either slow it down or make it more prone to error. One or the other.
So yeah, a Glock is more dangerous to holster. But it's also simpler, so you can focus on doing it safely (and slowly - most of the time there are no points for how fast you can get the gun back IN the holster). A 1911 is potentially more error prone to draw and fire. Google Tex Grebner. He focused on speed, rather than safety. Automatically chaining a sequence of events, such as flipping off a safety, then putting your finger on the trigger, in order to precipitate the proper "end result" in a prespecified minimal amount of time, makes things dangerous. Call it a holster design problem all you want, but he was basically training himself to automatically bypass the inherent safety of finger off the trigger by relying on a manual safety and "chaining" a sequence of events in a pre-determined amount of time (that works when things go right), and we ALL as humans do the same thing without deliberate thought and practice. At least with a Glock, the number of manipulations and the proper practice is simplified.
I don't care how many times I've done it. I always pause and consciously think about it when I flip on a safety, otherwise I won't remember if I had done it or not! No different that being conscious of the trigger when reholstering.
To call one safer than the other is making too many assumptions about the person and methods. Both can be safe, both can be dangerous. Glocks have the bad rep because they're used by so many police. And that after they transitioned from revolvers (with which they also had tons of ND's.)
Anyhow, any gun with an EXTERNAL HAMMER is more prone to ND than any striker-fired gun. Polls and posts like this show that without a doubt, manipulating an external hammer is one of the #1 causes of ND's. I've never seen data that suggest a manual safety reduces ND's. For every Glock leg/shirttail/holster malfunction, there's untold number of ND's that DIDN'T happen because the Glock manual of arms is so simple. If you compare Glock leg ND's to "decocking incidents" there's no comparison. The latter is by far more prevalent. And the former is not limited to guns without a manual safety.