In my opinion, after a user was created, ohai should be notified to reload passwd data, so ohai attributes for that user can be used in other recipes.
I'm not sure whether this should be added to the user creation itself as described here or at the end of the users::databag recipe (so creating 100 users would only trigger 1 reload).
I've been having issues with this as well. However, through research I've discovered it appears that Ohai attributes are constants set at the beginning of the run, and running an Ohai reload will simply fill in any missing values from plugins that were loaded after the initial run. So I'm not sure if it's possible to reload them during the same run, even though the second example in the docs shows just that.