Something like throughput in trials on some standardized machine could be an interesting criteria - it would test both your hashing algorithm and your permutations.
Having said that, I'm betting that the EY people chose this particular problem since highly-optimized algorithms are easily available to all - meaning that the amount of HW one can throw at the problem (and luck) will likely be the determining factor in who wins.
Which HW should someone use? Well, EY has a cloud computing program, and it's right there....
That is, I think, the point of this contest. Make a problem that's hardware-intensive, so that people will try deploying it on the EY cloud platform and get them into the proverbial front door of the product family. They're not interested in novel algorithms; they're interested in getting people onto their platform, and getting them used to it.