Is their website not separate from all the coins they hold? If so, they should be contacting all of their customers and offering to give them back their funds, assuming Livecoin still has access to them (which they should).
It could make sense that an attacker would place a backdoor to ensure he can reenter the server. What doesn't make sense, though, is how Livecoin acts. If your computer / server is compromized, you completely reset it to make sure it's not compromized, anymore.
Assuming they have separate control over their software, it shouldn't be too much of an issue to setup their exchange on a clean server, and assuming they have all their data in a database (hence the name lol), they could even move on with their business using a recent, working state of their exchange.
Sure, a shitcoin exchange isn't a hosted Wordpress. But even if it's more complicated, it's absolutely crucial to take these steps. And they'd be fine.
So, as nothing they say seems to make much sense, I tend to also side with this:
Not really, it looks like a childish attempt to fake a hack after an exit scam.
If the hackers got the money - why would they extort Livecoin? If Livecoin controls the funds - why would they pay the hacker?
If it was a real message from a "Hacker" they would have never had to use the term "livecoin" as it is implicit in the location of the post who was being refereed to. By using that term the scammers have outed themselves.
Not sure if that would hold in a court