There is something wrong about this story because such amount of wallet can't be a hot wallet, I have never heard of that exchange and that means they don't have much liquidity that much and that kind of Bitcoin should only be kept in a cold wallet, storing this amount of Bitcoin in a hot wallet means they don't care much about security of their custody if such amount of Bitcoin can be stolen over night, it doesn't make any iota of sense but proper investigation should help.

I also don't understand what comes next to the mind of scammers. Who steal such amount of Bitcoin when you can't spend it, the transaction will never step a foot on any exchange because it will be reported and even some exchanges should be aware of it by now since it has gotten to a media platform like Coindesk. The hacker would just be moving coins and wouldn't be able to spend, this is what physics means when you do zero work, noting is achieved here.