Very interesting, thanks for posting the link.
The skier needs to ask if he would ride that line without his airbag? his beeper? if the answer is NO then those bits of kit are increasing his risk of being involved in an avalanche even if they are important to survival, as was his helmet. His friend should not have moved him after the accident but phoned the S&R, a small spinal fracture can easily turn to complete paralysis if the person moves too much and after a drop like that off a cliff you could really suspect something, better to call the REGA/PGHM than risk it. He needed to be put onto a back board and neck brace and taken to hospital for a check over. We are not all Jamie Pierre!
ABS - he was riding above cliff bands, it is hard to tell the scale but an ABS may actually take you over the cliffs with the slide rather than stopping higher up, hard to tell in this case and hard to make a call in the heat of an avalanche. The ABS will naturally deflate which is probably what the skier observed with his unit.
He was very very lucky. A freerider with ABS was killed on the Mont Fort in Verbier a few days ago after being taken over cliffs. Someone I know had a similar fracture in a smaller fall during an avalanche and will never walk again.