I'm not arguing to disband the military. Of course we should keep the powder dry. That's a far cry from what this guy is advocating and celebrating. Advocating neutrality in foreign affairs while keeping american troops on american soil isn't some utopian pie-in-the-sky theory that depends on the inherent goodness of human beings. It's been tried before in our history, and worked well.
This still doesn't discredit my main point though. Let's say I walk into a notorious biker bar, get piss drunk, and start insulting everyone's mother. Yes, at that point, it would be smart to fight back. But that doesn't discredit the policy of minding your own business, which is what this guy is trying to do.
If we'd never entered WWI, it wouldn't have mattered if Hitler went on a rampage, we would have been just another faraway neutral country at that point. Even then, Hitler was going out of his way to avoid sinking US ships headed towards Britain, even when fired upon. That's why FDR was seeking to enter the european war "through the backdoor"--via provoking Japan with a gas embargo, and Operation Rainbow Six.
The civil war was not inevitable. The only thing necessary was for yankee politicians to let the south go peacefully. Again, this is not some crackpot idea like communism that requires the masses to be inherently selfless. It only requires pragmatic leaders. If I'm not mistaken, Switzerland allowed (or still does?) cantons to secede if they didn't like the central government. It has worked well for 800 years.