Exactly.
I am a bit confused by this article too. Was the issue that he wanted to wear his uniform, or that he didn't want to wear a gown over it? Looking elsewhere it was because he did not want to wear the cap and gown over it.
I highly doubt that student did not wear a cap and gown during the ceremony.
This...
You can wear whatever you want or nothing at all UNDER the cap n gown. But all students must wear the cap n gown to cross the stage.