> I fail to see how this would be anything other than theft if Bitfinex goes forward with this.

It could be part of a liquidation. If Bitfinex owes more than it has, then it's going bust regardless. This is just a question of how its remaining funds are distributed amongst its creditors.

I don't see how they could intend to continue trading, since creditors could individually sue them for the funds that they are owed.