This does not sound like a dividend but simply like hyper inflation.
Especially this is odd: "Please don’t try to abuse the system by buying and holding ETHDN a day before the Payout day, our team will check if you’ve been holding ETHDN for a month or not.".
The beauty of smart contracts is that they can automate stuff like this. Why do you need to check this manually? I and many others could come up with a smart contract right now that does this check by itself