Unarmed combat has worked fine with creature attackers since day one; I made sure that all the combat logic worked fine with any permutation of players and creatures for attackers and targets. Your defense against a creature unarmed attacker is exactly the same as it is against a player unarmed attacker.

The only missing component is the "AI" logic that will run it from the creature end. That can be tricky, for reasons that I think I've mentioned before. In a game like this, the intent of creature AI is to make the player feel like they're in a dangerous situation and a desperate battle (the prevalence of one-shotting makes this a lot harder to achieve). It is not to use the best strategy to defeat the player. The latter is easy; the former will take a bit more thought and experimentation.

I haven't yet had a reason to complete it because designing a new unarmed creature, or converting an existing one, hasn't yet risen to the top of my list. I think about implementing a shan monk every so often, just as an initial prototype unarmed critter. I may yet get around to it, or something similar.