Delirium,
It's a fun weekend trip, not "training". One visit to a military base to see their stuff is not "training".
At the very very worst, it's early recruitment. But not a single child was there without the express permission and encouragement of their parents, so even that charge would be weak.
You're right, if the national guard sponsored the yearly camporees and jamborees, complete with military-style competitions and actual military training, then it would be out of line. But a trip like this is just another life experience.
Heck, you may as well claim that the boy scouts are brainwashing kids to create liberal hippie tree huggers because in many (most?) troops, you have to organize and lead some sort of environment preservation project to become an eagle scout. Again, it's about giving kids life experiences that they would probably never be able to get anywhere else. When I went through 3 USAF survival schools, my scouting experience resulted in me being almost instantly at ease in the various environments we were put in, whether it was in 2 ft of snow in the colorado mountains or paddling around in a Florida bay in springtime. The guys who didn't have any outdoors or scouting backgrounds as kids were pretty easily identifiable, because they're the ones who were near panic the second the bus passed the last 7-11 on the road up into the mountains.
While Camping at Pendleton, we collected hundreds of expended dummy rounds and MG links, creating some 20 ft of MG belt ammo, and had fun pretending to be marines for a few days. It sure didn't turn us into jackboot thugs...