You can't completely assume that the reason why your 0.01 btc withdrawal request went into pending manual is because their jot wallet is empty, it might just be the way the casino's withdrawal algorithm is programmed to operate or function.
Disregarding the fact that bitcoin has lost some value compared to the previous price before touching its previous all time today, 0.01 bitcoin is still worth a little above $600, not a very large amount, but still possible the casino might have some limit to an amount the withdrawal algorithm can process automatically, and anything above that, will require manual processing.
You're probably overthinking the situation. The simplest assumption is usually the correct one.
If the reason was manual approval, then how come they allow much larger value withdrawals in other cryptos? Do they have special rules for bitcoin? That makes no sense.
And if this was the case, the customers should've been informed about such policy.
But the truth is, going through this thread, you'll see that hot wallets getting drained and not refilled happens quite often. It's especially understandable when BTC price skyrocketed, so many people decided to withdraw and cash out the profits.