The key parts of the article:

The court sided with state officials in the case, which pitted them against the White House over a 1996 federal law that bars people who are in the U.S. illegally from receiving professional licenses from government agencies or with the use of public funds, unless state lawmakers vote otherwise.
the court made clear the only reason it granted Garcia’s petition is that California recently approved a law authorizing the state to give law licenses to immigrants living in the country illegally
There is nothing for DOJ to fight against. States can make laws that allow this, CA did...more or less "end of story" unless Congress changes the federal law. Though I suspect the "state's rights" folks might get some new allies if congress did.

Whether or not the guy is fined for his non-citizen status (or turned into a high profile deportation), or should have been at some point in the past, is rather a different subject to the legal case about his law license.