Recently I found a page by Derek Ling[1], which shifted my perspective. I now think the point is closer to _balance_ than idleness. When it comes to goals, it means that you can have them... but don't expect to reach them. Goals give direction to your efforts. But in order to avoid suffering when life inadvertently gets in the way, hold them loosely.
The same goes for this story, I think. Not being useful is not going to get you anywhere, but being too useful isn't either.
An informative comparison of Tao Te Ching translations can be found here[2]. It shows how differently the same verse has been interpreted by different people.
[1] https://truetao.blogspot.com/2010/04/sage-has-no-goals.html [2] https://ttc.tasuki.org/