I assume that the “peaceful”, “americanized” muslims, would join in the frey because of the “brotherhood”. Is there such a thing as a muslim that would/could divorce themselves from the “extremeists”?
Yes, there are some. I know a few personally.
The problem for them is, they are considered by the radicals to be apostates.
In the Koran, there are, I think, four (but I can only remember three) approved targets for jihad:
1.) Apostasy
2.) Infidels
3.) Thieves
Bernard Lewis (who is/was considered by many to be the leading non-islamic scholar in the west) says that of these Apostasy has a special place at the top, jihad against those who believed in Mohammed but have recanted.