While this a decision each organization can make individually, it is compatible with sociocracy to have some people who are “only” doing work and who are not part of a circle. We sometimes call them “worker bees”. Obviously, their voices are then not heard as easily unless there is a good way for input. It is not unusual, especially in volunteer organizations, that someone might be doing work and being a circle member in one domain, but also carries out tasks that are within the domain of a circle that person is not a part of.
If a person needs to be heard on a regular basis by a certain circle, a “buddie-system” might help to hear their input.
In general, it seems important to emphasize that no one should be banned from being part of a circle without substantial reason, and no one should be forced to be part of a circle.
For more information, check out our handbook Many Voices One Song chapter 2