Thanks for the link, their whitepaper [1] is pretty interesting (they've put a lot of thought into the "network of trust" optimization I mention above).
Seems they use the bitcoin block chain heavily as the basis for trust and security. Both of their "proof of burn" and "proof of timelock" techniques require each user to have a complete copy of the latest block chain (currently >20GB) to independently verify global trust.
I mention a few other pitfalls with this approach in another comment [2].