He used that with his Glock. The 1911 had a BH Serpa. His trigger finger slipping off the lock was the problem.
No, he used improper technique on the Serpa release button--THAT was the problem. He tried to pull the gun out BEFORE disengaging the release button, and then curled his finger, and pressed hard with the tip of his finger, rather than keeping his finger straight, and sliding it up the holster, which will ALWAYS put your finger along the side of your gun's frame.
When you hook your finger, and engage the release AFTER you've started you end up using a LOT of pressure to disengage the release, and then when it lets go suddenly, the gun sort of jumps out of the holster and your hooked finger has a lot of pressure on it, and will almost ALWAYS go into the trigger guard.
Bad training, bad technique, and just all-around thoughtlessness in handling his equipment properly...
This is the MAIN problem with using different kinds of holsters--overcoming the muscle memory for one retention mechanism when you switch to another platform. And the fact of the matter is that the Serpa and the Safariland are SOOOO different in their release technique that what is 100% proper for one can cause catastrophic ND fails with the other if you get them confused...
If you have several guns, settle on ONE type of retention holster and stick with it across the board.
Switching guns poses enough problems with the variables in the "manual of arms" from gun to gun. Changing the operational procedures for multiple holsters is just adding one more VERY important (and potentially dangerous) variable to an already complex situation.
Both holsters are VERY good designs--but they are pretty much EXACTLY opposite in the way they work, and getting these two holster styles confused can be VERY dangerous, as we've seen in this video.
This ND was 100% Operator Error and could have been avoided. Period. End of discussion...