The readme file says

Skip access permission
This is a fallback overide, the fallback behaviour will not be followed
for users with the specified permission.

but when I (as site admin) have the permission, neither the "action" or "fallback behaviour" seems to occur.

Having set "action" to "hide", I was expecting the prepopulated field to be hidden, and thought that the module might be broken.
After creating a role with permission to create a node, but without the "skip access permission", and logging in as such, the field is now hidden.