It does not work to keep value over 10 USD, people does not park their coins if the value is lover than 5, also I do not understandt how they can give such interest and keep the value over a price, all interest will go to exchange and have a dump again. There are several issues that can effect parking proposal.
They have 1.5 Million from Premine, to keep that interest Rate for a Time and also part of the Block Reward goes to minex Bank.
But i have to agree, at some point in Time, they have to lower the Rate and that will lead to a Dump @exchange.