I find it funny too. And I rarely find his stuff humorous.
I think its funny because, though we control all branches of government now, supposedly, we still feel our free speech stifled at every turn. I can't scan this in but here's a Dilbert from the other day:
Worker: The great thing about Free Speech is that I can criticize the government.
Boss: I'd fire you.
Worker: I mean outside of work.
Boss: I'd fire you for that too.
Worker: May I express enjoyment of my pastry?
Boss: Sure, it's a free country.