This has been in the making for almost 3 years and has nothing to do with "sunset of the semi-automatic rifle ("assault weapons") ban".
It just seems that every time some piece of gun control legislation was being seriously considered during the Clinton administration there was a mass shooting or bombing. The anti-gun groups are doing what they can to muster for a renewed and intensified 'assault weapons ban', and use incidents such as this as poster children.
It is interesting to note that there has been relatively little of either (bombing/mass shooting--thankfully) since 9/11.
I do not claim to be privvy to operational details or timing regarding this group or any other, including the FBI.
It does seem that since the separation from Ranch Rescue things with this group are going overboard, but this is only part of the story.
I have read descriptions of large groups of invading illegals cutting through private property, trashing the place. And I have seen assertions that these groups include drug dealers, and that law enforcement is not effective in some areas at responding to complaints in a timely fashion. I can see where night vision equipment would be essential in trying to determine the composition of a group (adult males vs women and children), and whether or not the group is armed.
If my back yard were being invaded on a regular basis by large groups of people with the potential to be dangerous, I'd be sorely tempted to take what help I could get wherever I could get it.
Groups like the Arizona Guard can only exist to fill a vacumn, (sort of a neighborhood watch group). If there were no perceived need, the property owners would run them off themselves, and these guys would have to find something else to do.
If the main problem of border invasion is addressed, the vigilante style groups will go away.