No, I think you're absolutely correct. Most likely thing at this point is that they're gone. There are two other possibilities, and while they are things that happen, they're not terribly common. It's just too easy to communicate these days for me to think the other possibilities are at all likely.
First, they could have been hit by a ransomware attack that locked them out of website control and their social media accounts. If their phones run on VoIP, that could also take out the phones. This happens, but it's not exactly commonplace, and you would think that someone in Live Aquaria's chain of command would still have the ability to talk to people.
Second, they could have had their entire online control team either quit or get fired. Again, this happens, but even if it did you'd think that someone would have the ability to talk.
The simplest explanation that fits with everything we know is that they're gone.