Without wasting my time watching the whole thing, it appears the idiots went ahead and tried to do it.
All I can think of is since it is a military installation and people are warned about not crossing the border, and all the military personnel inside are sworn to defend the Constitution against all enemies, foreign and domestic, that the personnel are completely within their rights to use deadly force as authorized.
"Oh, they can't stop us all!" "Oh, we are pretty well spread out." Yeah, well you are at a military airbase with Bellis, Creech, Fallon, and others in the locale and they all have something called cluster bombs...
Guess they didn't think that through.
Now if they are just camping at the border to harass and be a nuisance, well, more power to them as they are not harming anyone and vice versa. But they are a little late. Every year in May, Rachel NV has Rachel Day which culminates in the "People's March" where they march to the border and party there all night, so it was cool before these guys even though of it.