He is just spamming to build rank.
The signed message doesn't mean much because if you read back a couple of pages he is just looking for someone to "say" they can bankroll the site.
He probably found some investor which will prove solvency by signing the BTC message proving he has funds with a message like "ZoomDice Bankroll funds" but in reality this investor never actually sent him funds to the site.
Its more of like a IOU or "agree" to bankroll if the site hot wallet falls negative, but since the OP doesn't actually have control of that balance it doesn't mean much.