He actually does not have the luxury. Unlike Fed, he has not met that criteria yet to have quite that freedom. The longer he's out and the lower his ranking falls the worse it will get for him.
From what I've read, I believe Rafa is putting his health and physical fitness above ranking points and fines... I think he's got those priorities right, personally.
Nadal is very injured to even consider playing AO'13, but then a day later he starts practicing on clay and broadcasts photos all over the internet?
The AO tournament organizers should be pissed.
I'm pretty sure tournament directors know the difference between practice and match play. ..Even I know that, and I haven't been following tennis all that long.