Yes. A classification decision is based on the facts as they exist at the time you seek reclassification. At the time you were admitted, you were assigned out-of-state status. You satisfied few, if any, of the criteria needed to be classified as an in-state student. Principal among these was that you were " ... Residing in the State of Maryland primarily to attend an educational institution." If you were residing outside Maryland at the time of application, UMUC assumes you were residing in Maryland primarily for the purpose of attending an educational institution. And, in fact, the presumption was valid. You had come to Maryland primarily to attend UMUC.
However, with the passage of time, your personal, professional, and/or economic circumstances can change. So, an examination of the facts in your Petition for Reclassification can now demonstrate you are residing in Maryland for a more complex set of reasons. You may no longer be here primarily to attend UMUC. For example, you might hold a job in the community, own a house here, have a Maryland spouse, or have children in Maryland public schools.
Your original out-of-state classification is not permanent. The presumption that you are residing in Maryland for educational reasons that was originally raised by your application from another state may no longer be valid. It can be rebutted with new facts. However, the burden is on you to present evidence to rebut the presumption. You should outline your reasons for living in Maryland as part of your Petition for Reclassification, and you are required to meet all the other criteria as well.