dunno, just check several services announced on Exchanges forum section where they don't accept gambling money so I became curious about the reasons...
There are few possible reason,
1. Gambling is illegal on country where the exchange operate.
2. Gambling is legal, but they don't want risk user deposit from non-licensed casino.
3. Gambling is legal, but funds from casino are deemed risky and they don't want take the risk.
It could also be a KYC thing. Centralized KYC enforcing services (such as exchanges) are forced not to accept any money that comes from any centralized service that refuses to enforce KYC (such as bitcoin gambling sites).