He didn't make a 'point,' he expressed a really dumb opinion, and made an inaccurate statement about the legality of the Constitution.
No, the constitution is not a particularly good example of its type, so that was not a dumb opinion. Also, I suppose it is 'legal' in the sense that the proper rulers of America - the British - had by that time given it up in some formal legal way. Still, there is no doubt it is a highly overrated peice of work.
I mean, my goodness, many people in countries without any constitution at all are much more free than Americans, so the thing can't be all that good.