I wasn't exempt. I did not serve, but I signed up and I was willing. (My girlfriend was none too happy about my willingness, either.) I'm probably ineligible now (depending on the details of the draft).
But if someone wants to eliminate the draft, or even if someone wants to turn the US socialist (and I would prefer even Bush to a socialist), you don't tell them to leave the country. These are legitimate opinions, that's the whole point of democracy.