Do you know what a psyop is? The point of the behavior was the photograph. The point of the photograph was its publication. The point of the publication was to create disdain for military sacrifice. The point of creating that disdain in the public mind is foment REBELLION.
Too farfetched? Then you're going to have to come up with a "reasonable" explanation for National Guard soldiers mocking the scaredness of their own work - a sacredness they are acknowledged for throughout the military, and which is the most pervasive part of their training and operations. This whole thing screams psyop, as it is utterly inconceivable that these soldiers would even remotely think of this as a "prank."
hurry up and wait* in the regular army, in the National Guard multiply the bureaucratic effect by 1.5 to 2.5 and you're probably in the right ballpark.
* Kind of like pre-pre-pre-formation formation; where the commander puts out that formation is at 0700, the CSM says 0630, the 1SG says 0600, the platoon leader says 5030, the squad leader says 0500… because the formation is at 0700. … What are you going to do when you're required to be there for 2 hours, with absolutely nothing else as a purpose?