"Muslims" who don't really believe in Islam aren't really a problem, are they? It's a bit of a red herring to say that an example "Muslim" who pretty clearly rejects central Islamic doctrines (e.g., "Dar al-Harb") is typical.
Nope. They aren't, but there are plenty of Americans from Muslim countries, who are pretty much normal people and not a threat. They may identify as Muslim, but 80% of Americans identify as Christian, and many of those are not particularly observant either.