Yes, but my point was that once that user has logged off, someone else can use the same credentials. That creates a new session and allows the second person to use the first user's credentials, just not at the same time.
"The goal of this authentication plug-in is to make sure that each user in Moodle only has one active session simultaneously."
If that's fine and works for you, that's great, but its not what you appeared to ask in your original post. There is still nothing to stop the users sharing their credentials, only to stop using them at the same time. That will work, if its in combination with some of the things I suggested such as synchronous activities such as chats, but won't prevent multple users of the same account accessing resources. Again, not a problem if it works for you, so long a you are aware of that fact.