The perfect theft in crypto is claiming that a project or an exchange is hacked when its all an inside job, the reason why I think about this is I have never heard about other top exchanges helping a exchange that just got hacked to track their funds and get some back at least but if it's a sole hacker from outside they will track him or them down, why is that?.
It can be true, the creator of exchange is waiting for the perfect time to exit scam and as you said it is not possible to find whether its an insider job or not but even if the exchange is not tracking still some of the address are known to the public which can be used to track and where all those funds went and laundered into money.