Furthermore, allowing people to maintain their lifestyle with minimal interaction with the state is probably the best possible use of the state in the first place.
Military forces are a separate problem from legal problems. I think rather a lot of the people rushing to correct me are conflating the two in their heads. When you say "just being taken by other Americans", are you thinking of a rogue criminal or some sort of organized invasion?
Personally, I suspect that even if you tried the sort of organized invasion that a civilian might try to put together that you'd still find yourself up against some stiff resistance. Criminals in general are less than excited about stealing from people when they can almost count on being shot at. They steal from people who won't shoot at them.
The problem is when you get to military levels of invasion, at the level where you start putting together forces that count on being shot at and still overpowering you.
Sounds like a militia.
Also, you don’t seem to be being taking seriously what it means not to have a legal system.
For example why are you talking about criminals? If there is no legal system, there are no criminals. A bunch of guys with AR-15s and pick up-trucks and walkie talkies really wouldn’t find it hard to displace a religious community who are relying on old hunting rifles, horse drawn buggies, and no wireless comms, especially since the Amish would have families to protect.
They'll only need to make an example out of a few people to make it clear that giving in to their demands is much cheaper than fighting them.