And who is wrong...

Courtney is wrong.

There is a third law of thermodynamics

The third law of thermodynamics is an axiom of nature regarding entropy and the impossibility of reaching absolute zero of temperature. The most common enunciation of third law of thermodynamics is:
“As a system approaches absolute zero of temperature, all processes cease and the entropy of the system approaches a minimum value.”

It can be concluded as 'If T=0K, then S=0' where T is the temperature of a closed system and S is the entropy of the system.
The essence of the postulate is that the entropy of the given system near absolute zero depends only on the temperature (i.e. tends to a constant independently of the other parameters).