What makes me curious is, what the reason from the hacker to hack unpopular site like sicodice?
Money? I do not think sicodice has good amount of money (bankroll on the hot wallet) so I think it does not worth for the hacker to hack sicodice.
High likely, it is just a trick from the owner to run away with people's money and made a lie that the site has been hacked.
I have no account in this site, do they have official social media accounts?
Disregarding any related thing about inside jobs, either these hackers think that
a.) the site doesn't have tight security and supposed to be easy to breach
b.) they are doing test hacks or
c.) they are really targeting small websites thinking no need to do such more technical ways to breach the system.
As you said, the site might not have a good bankroll so I think the owner won't just run away to take money if the purpose is really to scam people. In most cases, an owner that has a suspicious activity will put the site as an active to take chances that someone will still deposit.