Obviously. The point wasn't that nukes are like vaccines, the point was that, like vaccines, we've gotten so used to life with them that we've assumed things would continue on exactly the same without them, and thus start trying to get rid of them because of perceived secondary issues.
Stopped us being invaded. Eastern Europe and the Middle East? Not so much.
Most people in the world aren't Saturday Morning Cartoon Villains. If someone can do something without threat of reprisal, they're significantly more likely to do it.As I said earlier, anyone insane enough to trigger Nuclear War is not going to be put off because they might get nuked in return.