I think security would need to have a different set of objectives. If they were antagonists in the traditional sense, they'd risk being too powerful but also would mean there'd be one fewer person to help combat antags.
I quite like the idea of the "bad officer" objectives. Ones that encourage them to still do their jobs but in a way that doesn't detract from other players' experience. Stuff like the old "break someone's bone to teach them a lesson" or new ideas like "You hold a grudge against X, ensure they spend at least 15 minutes in a cell".
