When it comes to government property, you can allow all displays or no displays.
MORE: http://www.patheos.com/blogs/friendlyatheist/2014/01/02/arkansas-judge-defends-courthouse-creche-but-forbids-atheist-sign-since-itd-open-the-door-to-hundreds-of-displays/
See also...
AHA: Arkansas County Must Remove Christian Nativity Scene From Government Property
http://americanhumanist.org/news/details/2014-01-arkansas-county-must-remove-christian-nativity-scene
Judge denies atheist equal representation in Mountain Home, Arkansas.
http://www.patheos.com/blogs/wwjtd/2014/01/judge-denies-freethought-group-equal-representation-in-mountain-home-arkansas/