I don't think it is wrong to assume that at all. UCR's post bacc admission guidelines state that "Preference will be given to applicants from the Inland Southern California region." I wouldn't let this guideline keep you from applying though; especially if you just live a couple counties away from wherever you are applying. You never know how your entire application will inspire them to invest in you, despite where you live. I think a lot of post bacc programs, including UCRs, are interested in applicants that are dedicated to serving in medically undeserved communities considering that the ultimate, down-the-line, goal would be to transition these communities out of the "medically undeserved" status. So I think that if you are seeking to get into a post bacc (with a "medically-undeserved" mission) that isn't within your county, you should focus on how you can serve a community (or communities) within your own county that has (or have) a similar "medically undeserved" status as the county you are looking to obtain your higher education in. This shows that although you might not directly serve, for example, Riverside County...you are experienced in serving medically undeserved communities, in general, within your own county. OR if your county doesn't have a similar medically undeserved status, it would be good to step outside of your county and see where you can serve. On top of that, and maybe most importantly, you will want to do some research into the out-of-county post bacc to determine a reason of why you want to participate in that program specifically. Admissions really want to know how their program will benefit you in a different way that another program will. What makes their program stand out above the others?
Trust and believe I still have a lot of learning to do! Like I said UCR's post bacc was the only one I could/wanted to apply to. Reason being is because I still want to serve Riverside/SB county through the non-prof organization that I am in. I still want to continue to learn how to effectively serve in undeserved communities; even though, for the next academic year, I will have to reduce the amount of time dedicated to it.
I would be more than willing to help as much as I possibly can with any questions you have. I know the general spirit of higher education is competitive (which I still don't understand), but I want to take the collaborative approach. We will all be future colleagues after all!