I think hedge fund's founders motivation behind this idea could be like this:
Let's give many people some [encrypted] data to play with. May be someone will find a curious and unexpected pattern we didn't looked at before. May be this idea won't be workable straight away but we [hedge fund] are going to investigate this idea further and probably use this in our trading strategy.
In short, they are probably doing ideas mining using power of crowd.
From the competition rules: "You retain all intellectual property rights to your model. You never have to tell anyone how you built it and you never have to tell us who you are. You only upload your predictions."
Let's give many people some [encrypted] data to play with. May be someone will find a curious and unexpected pattern we didn't looked at before. May be this idea won't be workable straight away but we [hedge fund] are going to investigate this idea further and probably use this in our trading strategy.
In short, they are probably doing ideas mining using power of crowd.