Capt. Stable
Thankfully, I've never been involved in such a situation. However, the type of incident's where removing the bridge would be necessary, would be a Terminal fire. There is the risk that the fire spreads down the bridge, and potentially reaches the aircraft.
That situation is also possible in reverse. The greater danger here is that people will become invloved in a rush either up the bridge to the Terminal, or down the service steps to the ramp. Either way, the risk of people falling over each other would be too great, and therefore it's better if the chutes are deployed.
John,
I can see your angle on this, however, at the end of the day Jetway's are just another piece of Ground Support Equipment, although a helluva lot bigger and heavier than the rest of it. When you do your walk round, are you not aware of other vehicles and equipment moving around you? I presume you are; therefore, why should the bridge be any different? Do you request chocks on your Belt Loaders, Scissor Lift, or catering trucks.
As I've written before, apart from the warning bell, the orange beacon on the wheel bogey will always be (or should be) flashing, thereby signaling that the bridge is about to move. Also, when the bridge is connected to the aircraft and in Autolevel Mode, there is no risk of the bridge being able to move horizontally, only vertically keeping track with the aircraft.
BB