Adding multiple altcoins won't be a big problem for him. Because most coins are minted in just a few chains. As EVM wallet is always same for all EVM chain tokens. Tokens on the SOL chain have the same address. So they can add any coin they want but the maintenance hassle will increase a bit. And I don't think a casino site needs to have too many memento methods. Only few coins are enough like BTC , BNB, ETH , USDT , USDC , SOL , TON , NEAR , LTC etc.. Focus should be on speedy processing rather than paying attention to payment method
It always has risks like if Oracle doesn't work accurately, it will create holes for potential exploitations. No platform want to be exploited by hackers, so it looks simple by adding new altcoins or tokens, but risk actually exists.
As users, you can not mind about it but as a business owner, and operator, they will have to consider about cost, risk and benefit with many assessment technically and financially too. Having top cryptocurrencies for users on their platform, is good enough already. They can add more and make impression that they are professional, and adaptive to new trend as well as their good dedication on bringing more convenience to their users.
However, professionality is also shown by their well thinking about technical challenge, and manage risk that actually brings benefit to their business and users too. No users want to have issues with their fund on any platform, and it's kind of professionality of a business operator.