dumpsterDiver:
To say that you would yank your reg back if the diver didn't stop panicking is crazy. Either you are a buddy who will risk your life for someone or you are not a worthwhile buddy. (Are you only gonna help if they don't really need it?)
First, to setup the situation the OP posted. Already sharing air. Buddy bolts for the surface from 100'. When I say bolts, I mean bolts kicking hard and doing whatever to get there. IE, panic. A miscommunication would be solved when he got to end of my reg hose and noticed it didn't go up with him. That would result in controlled ascent etc.
I agree with you, having seen two divers panic underwater, the timeframe is very small to act. Also, once a diver hits panic - they are out of control. They are on instinct - period and instincts are bad things underwater with scuba.
Now reactions. I would guess many divers would ride the escalator simply because they didn't react fast enough to prevent it. Most of the actions mentioned - grabbing the inflator, going for the tank etc merely put you in a different position for the ride. and the surface. Only radically getting negative will stop this from the get-go, assuming you can hold them at the same time as getting negative. (steel doubles help here). At this point, depending on your skills, you may be able to control an ascent (best case) or more likely, loose them to a solo ride to the surface.
Me and my reaction of sending them up solo is based on a simple premise. I have already done my best for you under the situation. You ALREADY HAVE MY REG AND AIR and you still panicked and bolted? At this point, I need to look out for me so I can be of assistance later (or at least not another victim). Call it selfish call it whatever. I subscribe to the notion that you do what you can when you can but this case, they are already beyond help until they get to the surface. (panic causes that).
At 30' I'd go to the surface and skip a stop. I wouldn't necessarly ride them up but I would be very close behind. From 100' I want a short stop along the way ( 1 minute or so). Rapid ascent from a deep depth coupled to exertion helping the paniced diver is not a good combination for avoiding the bends. I would only risk that for a loved one (child, wife brother, basically someone I would die for)
As I said, call me evil, callous whatever. I just realize there are times in diving that you can't 'save' your buddy.