Tether can freezer your fund as long the fund is in your wallet but if the tether goes to centralized exchange that tether can freeze it since the usdt are in the pool of other clean usdt.
But there is a catch if you contacted the centralized exchange that the CEX can freeze your account and that is the best way for it.
None of them can freeze hackers' accounts unless directed or requested by law enforcement. Based on the request of a regular user only and if the amount has nothing to do with money laundering or terrorism then freezing the amount will be more difficult no matter how much evidence you provide.
OP's brother stores his assets in his personal wallet and on his computer, which means he has nothing to do with OKX. How could they easily believe what he said based on just the few pieces of evidence he presented? If I were an OKX employee, I would ask him again why he didn't report it to law enforcement?
While I agree that they can't take the money from the hacker and give it to OP, they can definitely freeze if there is any proof provided, until it's cleared. I have seen this happen before, all you have to do is just talk to your own lawyer, tell him to open an appeal, as in just first part of the sue process, without even going to court, just basically a piece of paper and when that happens, you also send a copy to it to OKX or any exchange, any proper exchange would freeze the account until the court decides on what is going to happen, which will not be a bad idea in this case if OP could do.
All of this starts with contacting a lawyer, without a lawyer you are not going to be able to do anything, after the lawyer part, lawyer will handle the court side of things, but then you can handle the exchange part as well. Not that there will be any results because we will see 99.99% of the time hacker is from another nation and won't care, and nobody in your country would are neither.
Unfortunately, I agree with you.
Without some officials, either from the government or private, OKX may not even consider doing something in such a situation.
They need - some - proof to do something with the assets of the hacker, and that would be a good step in starting to resolve this case.
