Oh understood, so it's like a big mining pool. So no one can control the address. No one will, basically, more correctly.
No, not exactly, not a pool, an exchange... And there are defenatly people that can spend from this address. Ideally only employees of huobi.
These funds were sent to huobi by people having an account with huobi. They keep their funds on this exchange because they're either not familiar with the many, many, many risks of using an exchange as a wallet... Or because they use their balance to trade on a daily basis.
If an employee that has full access to this wallet decides to rob his/her employer, he can defenately do so. If a hacker or a physical thief can get his/her hands on these funds, they're gone. These are not mining rewards, they're the lifesavings of hundreds (maybe thousands) of customers.