This is how I see it:

Alinghi pumped to turn downwind, but not all the way. After the rudders were back in the water, they started to turn upwind, but not all the way once again. Maybe they just wanted to return to the previous heading. I guess they thought the gust was over.

Holmatro did about the same: bore away to avoid the pitchpole and turned upwind after control was regained. The upwind turn was probably in response to Alinghi's. I believe both upwind turns were tactical, not for depowering.

The difference is that Holmatro did not stop turning at their previous heading like Alinghi did. For some reason they decided to keep turning upwind. This last (and critical) decision may have been for tactical reasons or for protection, but whatever the initial reason, it became a depowering manouver in the end. Holmastro may have dumped the main as well, but I can't see this so clearly.

It is interesting that immediately after Alinghi stopped its upwind turn and held course, Holmatro heeled more than Alinghi for a moment due to different centrifugal forces acting on the boats.

I think Alinghi would have survived if the spi wasn't partly unfurled.

I'd say two things account for the different outcomes:

1) Holmatro's stronger commitment to luffing.
2) Alinghi's unfurled spi.

Quite instructive.