Why can't I Update Candidate Status?

Why can't I Update Candidate Status?

Hi, In all your blueprints, workflows etc...why can't I update candidate status ? For example, I have lot of profiles coming from Facebook but are mostly JUNK and miss lot of required information. Right now, I go through this JUNK manually and reject those profiles. Instead, I want to be able to write a Workflow Rule or a Blueprint to go through this process and update candidate status to "Rejected". But Update Field action in both Workflow Rules and Blueprint is missing the Candidate Status Column. Why is it so ? Niranjan