No court has as yet ruled that the OSI definition of "open source" is the legal definition of the term. The ruling here does not either. If it had limited its ruling to the term "open source," then this would indeed begin to codify what "open source" means from a legal standpoint.
However, the courts ruled upon the composite term "open source and free". Under the OSI definition, open source implies free. But no court has yet so ruled.