Upper-class Air Force cadets are military personnel and may be subject to travel restrictions under the shutdown, per Jackson and Wagner.
John Taylor of College Football Talk also ponders if the impact of this situation will reach beyond this isolated game:
One thing that isn’t clear, and what we’re attempting to clarify, is whether Army and Navy upperclassmen fall into the same category as the upper-class cadets at the Air Force Academy.  If so, the shutdown could impact a handful of those games in the next month: Army at Boston College this Saturday; Army at Temple Oct. 19; Navy at Duke Oct. 12; and Navy at Navy at Toledo Oct. 19.
Additionally, Army is scheduled to travel to Air Force Nov. 2.