The Marshal and Deputy Marshals of the Customs Court are not authorized by 18 U.S.C. § 3053 to carry firearms.
Neither the official duties of the Marshal, as described by 28 U.S.C. § 872 and Rule 19 of the Rules of the Customs Court, nor the official duties of the Judges of the Customs Court would appear to necessitate the carriage of firearms.
If the Customs Court finds it necessary to rely solely on its Marshal to police its quarters, it would probably have inherent authority to authorize the Marshal and Deputies to carry arms; however, there would be no basis for assuming inherent authority in the Court to authorize possession of arms by its Judges.
A state could not constitutionally require a federal official whose duties necessitate carrying firearms to obtain a firearms license.