These people didn’t even have a second to waste.
A good debate in the gun world is whether or not you should carry your gun with the chamber full or empty.
The video below shows why a full chamber is better from a defensive stance.
Chambering a round takes two hands. Everyone teaches people to chamber with two hands because it is the fastest way to do it. If your support hand is engaged in a bad guy or holding someone or is injured, you’re out of luck.
Range masters may teach using the rear sights to hook on the edge of your boot or belt or whatever, but those are small targets which are hard when someone is stabbing you or bashing you in the head.