That depends on how you define 'admins', doesn't it. When you have two classes, 'academic' and 'admin', and only professors are 'academic' - well then everybody else is 'admin'. It may sound weird and yes it's outside of the normal usage of 'admin', but in universities it's not uncommon to have this sort of division. It's driven by two things: first the historical context where you had lots of 'academics' who were all professors and had actual secretaries, and very few 'overhead' people like those managing buildings and activities etc (whereas now that's very different, because of the different role of universities); and secondly by the recent trend of keeping the number of 'academics' low because they can't be fired and are expensive. But you still need to hire people, and if they're not 'academics', they're 'admins', even if they don't do what is in common usage seen as 'administrative work'.