Also FAR rules to do not "trump" advisory circulars. If anything it would be the other way around because they are special provisions above and beyond the laws of the FAR, no different than an amendment to the constitution.
You cannot lose your pilots license for not following an AC, unless doing so caused some other rule to be broken. I am a pilot although presetly inactive and know this to be a case when I did fly. Also FSDO's can apply further restrictions above the FAR and AC's when they feel they have special safety requirements to do so. The FAR's allow this and if you break one of these regional rules then you can be in trouble, but it is not breaking the AC that gets you in trouble. They can site an AC when doing so, but that does not make the AC a FAR, and certainly not above a FAR.
I would think Master Blastes contacted the FAA and recieved a waiver, but I am not certain it would waive the 400 foot AC. But then unless they were near the LA FSDO they were probably OK because the AC is voluntary.