Another way to interpret this (and I don't mean it pejoratively at all): Demis has been optimizing his chances for winning a nobel prize for quite some time now. Releasing the data increased that chance. He also would have been fairly certain that the commercial value of the predictions was fairly low (simply predicting structures accurately was never the rate-limiting step for downstream things like drug discovery). And that he and his team would have a commercial advantage by developing better proprietary models using them to make discoveries.

Also since selling Deepmind to Google, it's Google's shareholder's money really.