Hardly semantics, School and University are not the same thing.
Anyway, it's not even about the University he went, it's about what the fact that so many people involved in politics and the media in the UK, are specifically Oxford PPE graduates and, that if I was the sort of right wing whinger who bleats on about elites ruling our lives, I might use that fact for some choice bleating. I was appreciating the irony.
It's not even a party political thing because, historically, it was the Labour Party that was dominated by Oxonians.