90s mascots were so random. Like why an owl with a graduation hat? He just graduated, so now he is wise, and can offer insight into lollipop licking? Was that his major?
"Until the second half of the twentieth century, mortarboards were often worn by schoolteachers, and the hat remains an icon of the teaching profession." [source]
So they weren't saying that he just graduated, they were saying that he was learned (the tortoise even says, "he is the wisest of us all").
That's how it used to be. You asked questions to people who were believed to be wise, and then their answer was what the truth was. And most of the things we "knew" were just wrong.