I started a discussion on this topic a while ago for exactly the same reasons you stated. I did a search a while back in which I pulled up a number of different courts' websites around the country. Virtually all of them had a page about jury duty. Many noted that jurors had to go through security, but none had anything about refusing to be screened -- i.e.: declining an administrative search. I agree -- if you are summoned for jury duty, you are not attempting to enter a courthouse voluntarily or as someone involved in a case. My non-lawyer view is that the summons states that you have to report to the courthouse at a certain date and time. I would assert that showing up at the door, but declining to go through security, meets this requirement. If the upstream story about Denver is accurate, this judge really would have set up a great "administrative search" ruling.

FYI, I found one article about a judge somewhere who brought his jurors into the courthouse through his private entrance because he believed that jurors didn't have to submit to a mandatory "voluntary" administrative search. He couldn't get the chief of police to let jurors get in without a search, hence the use of his private entrance.