Wow - that sounds nasty. Poor old thing. Good on him for playing on, it can’t have been easy.
At first, when they indicated he played on with a cracked rib, I thought he had been brave to continue. A pneumothorax is a completely different thing. Severe blunt force from Houston's elbow -enough to impact both rib and lung would lead to lack of oxygen and chest pain at the very least. Madness to play through that. Danger-ous in fact.
Anyway it must be limited, as he was released and driven home from Adelaide, in which case a conservative 3-4 weeks would be my guess.