Gary I agree with you, such a category does not have much benefit, as the Wikipedia entry shows there are hundred's of thousands of people that currently work for the federal government across the country. And a huge number since 1867.
A category should group people who have a time or a place in common. People who could have other connections to each other because of where they were, what they did.
In this case unless there was something special about the actual office she worked in, such as other relatives who worked in the same place, or other happenings such as Emily and her co-workers were all working in the office when some significant event happened. That would mean you would need to know who the other people were and how it-whatever happened-tied them together as a group. That would also mean you would need to create profiles for other people in the same office.
You could create a sticker, but again it doesn't have much benefit.
My personal opinion is we have too many categories that are unnecessary and not beneficial, including her job title and employer in the biography is enough.