Joe Conason, So George Washington was a socialist, too!
If the individual mandate is unconstitutional, how could our first president require every citizen to buy a gun?

The Militia Act

What would the penalty be for not complying with the Militia Act? Loss of citizenship?

As I made the point on FB, if there is a duty of the citizen to be in a militia, then requiring that he arm himself so that he can be effective isn't a stretch. If he "chooses" not to serve in the militia, then he should be stripped of his citizenship. This is one stop where the comparison fails.