"Unprepared" is a call made in hindsight.
Prepare, its an action verb that is done beforehand, by definition. How well you prepared can be evaluated in hindsight, but that's too late. If their ultra-light gear was inadequate, then there's a debate to be had, but if they didn't carry ultra-light gear, then they are simply unprepared.
In my opinion, an ultra-marathoner doing a long distance training run over a 24-hr period in the wilderness should carry basic survival gear regardless of the weather forecast. Maybe a little more than I describe, like rain pants, maybe a bivy sack, or maybe a little less if conditions are perfect. During a race, there are checkpoints and support, that's different.
To go without gear is not ultra-light, its infinitely-light and totally unPREpared.
