I'd say they Could if they were Organized in a Crowd of Americans, Woodstock Size.
Or maybe even much Less.
That is unless like in that alien movie with Richard Drifus ,
They have the ability to put them all asleep
The problem is going to be getting there, and what little parking
area there is, it's going to fill up fast (like a couple hundred cars).
Just the amount of water that many people would drink could cause
water shortages in the whole area.
All the LEO's would have to do is block off a couple highway junctions
and that's the end of it. Mostly 2-lane paved roads, and Groom Lake
(where any facilities are located) are many miles inside the perimeter.
The closest medical help is in Vegas, and that's 90 miles away.
I know that country well, and unfortunately lives may be lost just because
people are being stupid. Most of the base is not fenced, but there are loads
of signs telling potential trespassers that Security will shoot to kill...and
they they ain't joking about it.
At least Woodstock had outhouses...
