If I had to guess, they may have access to those keys, but they were probably informed not to access those wallets as they were probably accessed by the attackers as well. Meaning any activity is probably deemed criminal at this point, or any additional funds may be seen as something they can use if there is further activity. Either way, I don't see you getting your funds back; similarly to if you sent it to an incorrect address that ended up in the hands of some unknown person.