I believe you may be mistaken about 15.2-915 being germane to the issue. The law regarding firearms in courthouses is at 18,2-283.1
Of interest is the case that defines what part of a building constitutes the courthouse. That is Egerton v.Hopewell, 193 Va. 493, 69 S.E.2d 326 (1952). *§ 18.2-283.1. Carrying weapon into courthouse.
It shall be unlawful for any person to possess in or transport into any courthouse in this Commonwealth any (i) gun or other weapon designed or intended to propel a missile or projectile of any kind, (ii) frame, receiver, muffler, silencer, missile, projectile or ammunition designed for use with a dangerous weapon and (iii) any other dangerous weapon, including explosives, stun weapons as defined in § 18.2-308.1, and those weapons specified in subsection A of § 18.2-308. Any such weapon shall be subject to seizure by a law-enforcement officer. A violation of this section is punishable as a Class 1 misdemeanor.
referenced in http://www.virginia1774.org/CourthouseArea.html What do you want to bet the temporary digs include areas that do not meet the definition of a courthouse as set out by Edgerton?that only that portion of the building appointed for the use of the circuit court constituted the courthouse
* Sorry, but I can't give a direct citation to Egerton but on-line records do not go back that far. The cited case makes reference to it and quotes the pertinent portion of the decision. Take what you can get or pay for Lexis/Nexus on your own.