I'm no risotto expert, but I did cook it once (never again). Done correctly, it takes one person, with constant stirring and attention, over 30-min to make. It can't sit around once it's done or it will turn into a near-solid mass that will stick to the wall and never move.
So, it can't be made "on the fly", and it can't sit around too long. Cagney's obviously serves it enough to make it work (although many of us can attest to au gratin potatoes that were well past their prime), but since it's not tagged as vegetarian, it's likely made from beef stock. You can't just quickly "throw together" a risotto made from veg stock as a substitute (without using the aforementioned Minute Rice).
I've never ordered it at Cagney's, so I have no idea if it can even be considered a true risotto.