Actually, it looks like you understand their mindset very well. I also agree with your second paragraph. (My biggest disagreement with open carry is, in fact, your final sentence.) I suspect that the ratio of 'sane ones' to 'fucknuts' is probably much higher, but the sane ones are generally very low-key about it, and the fucknuts are just so loud.
That is pretty much the problem with all groups...ever... and why stereotypes and generalizations exist, (aside from making ti easier for people to insult eachother) because some asshole somewhere had to go and actually make it a thing.
The worst of humanity will always be the loudest and most violent part that we see. But we need to always remember the good parts and that not everyone is 100% of something. Not even 50%...its like 40% at the most. Edit
: Still the people who pull stuff like this have what's coming to them. There are other ways to be heard and when even other militia groups are calling you out and saying your wrong, you should really take a moment and wonder if itd be best to just give up to the boys in blue and not drag this out for the people who actually do pay their taxes.