3 years ago (nearly) since that comment. There are standard settings for worlds, so it's possible the system has changed since then. The morale system has had different settings for the same size worlds in the recent past, leading to the change once the world had launched on at least one occasion.
Either way, it's unlikely a simple formula will be used as many variables are no longer inter-dependant as they were in the past. A standard number for each size world is more likely, but with the ability to change it that wouldn't be available if it was a formula.