I agree. When thinking about the use of "proper" English, I find myself conflicted.
One the one hand, I truly believe that languages evolve, and it's silly to put any one particular version of English on a pedestal. That includes the version(s) one might associated with English speakers who are well-educated and/or wealthy.
On the other hand, I was raised to speak "proper" English, because my father believed that it strongly affects others' first impressions of the speaker's intelligence. I think my father was right about that, although I'm still undecided about how much it matters, and whether or not it's a concern worth catering to.
Alternatively, if you're using it by itself as an adjective, obviously it will take the appropriate gender. You don't need an explicit noun if you're happy with an implicit "man", "woman", or "thing".
If you're using it by itself as a noun, it's 2nd declension and the ending changes only based on plurality or case, not the gender of the actual graduate(s)