I don't think security is a big issue. She goes from her house to her office. Unless someone breaks into either one (or snags it on the train), I don't think her bike is at any risk of theft.

Whether a road bike is just as good as a commuter probably depends on your circumstances. Personally, I'd like to commute on something that has fenders and platform pedals and maybe fatter tires, depending on the road conditions. Any extra weight should be work-related stuff, rather than cycling shoes, a change of clothes and other gear. If I had a shower and a locker at work, it would be different. Not sure what her situation is.