I've always interpreted the requirement for professional sysadmins as referring to the job a person is doing and/or their ability to present issues here in a professional manner rather than membership of a professional association. While the latter is something I'd love to see in the industry anyway, it shouldn't be a requirement for posting here.
In other words, I see our requirement for professionalism as a quality bar for questions, not a barrier to entry for people asking those questions.