Any idea what kind of permitting or permission they had to go through to launch this? I'm assuming you can't just take what's basically a missile and go into the dessert and shoot it without the FAA knowing about it.
Of course the FAA doesn't give out such waivers willy nilly, they expect the amateur rocket community to minimize the need. Thus there are launch sites in the middle of nowhere that have launch windows where the big stuff is allowed.
They also self-regulate on availability of the big motors. The guys who make them won't sell them to anyone who isn't certified, other than as part of a launch to get said certification which is done under the supervision of someone who is certified. They don't have the force of law but so far it's worked. (And there's the separate issue of the hazmat rules about those big motors--most people can neither legally store nor transport them. Take delivery at the launch site and use them.)
A little higher (150km) and this would've been out of the realm of amateur rocketry entirely.
I’m sure you would get punished but what are they going to do about your rocket once it’s up there?
Launching at BRD is where I first met Elon Musk where he was there with 5 sons (at the time) to watch them launch golfball nosecone rockets with 3d printed fin cans.
There is an annual competition that precedes the main event called ARLISS.org