And why would the hacker communicate with them? To get a prison sentence and a nice bunk bed with some sketchy inmate? They are probably off the grid already and all the money is laundered and funneled in offshore accounts overseas.
Yes an inside job is more likely here. Whether or not the owners were in on the hack is the main question. Maybe one of their top employees knew the ins and outs of how Bitfinex secures the Bitcoins and found a way to get access to them. Maybe the hacker may even be someone from inside BitGo, the wallet provider by Bitfinex.
Im thinking the same thing too, its very impossible for an exchange to be hacked so easily which they have already the most secure in terms of holding huge volumes of bitcoin. They are already aware on such situations that might happen but there are really greedy people would really intent to get those huge amounts and as we all know that already reach millions of dollars and would surely be tempted to put a mission even to those staffs itself. Just my speculation.