Wolfgang Amadeus Mozart, baptised as Johannes Chrysostomus Wolfgangus Theophilus Mozart, was a prolific and influential composer of the Classical era.
The above line is cited from the article on Mozart in Wikipedia. As all English learners learned, the non-restrictive phrase "which is (was)" or "who is (was)" must be always left. In this line, however, it seems that "who was" is omitted before "baptised as ...", that is, I think it should be like this:
Wolfgang Amadeus Mozart, who was baptised as Johannes Chrysostomus Wolfgangus Theophilus Mozart, was a prolific and influential composer of the Classical era.
Why the non-restrictive phrase is omitted? I need justification for this matter. I'd be so happy if I could solve this.