It's the kind of punchline whose brazen cynicism you have to admire, no matter what the political clime of the day. Garfield does not just propose that incarceration may be necessary when crimes have been committed. Nor is he saying that having personal freedoms stripped may be necessary when an individual proposes a substantial threat to the safety of society. Garfield says unrestricted liberty has been ignorantly championed, because it is dangerous.
Is Garfield really a fascist? I doubt it. His rebellious streak is too strong. Garfield's closing comments are usually to be read as sarcasm, and today is no different. "Freedom is overrated" is simultaneously the reasonable conclusion of fear of others, and the ill-reasoned results of a flawed premise. Since Garfield's goals are unambitious to start with, if we subtract the quotient of his cynicism and self-pity, the philosophy is better stated: YOUR freedom is overrated, while mine is sacred.
If one extrapolates Garfield's combined beliefs and desires to a logical conclusion, everything in all creation - except the fulfillment of basic hungers - is overrated. So don't be too shocked when that includes your dearest ideals.
Also: That dog's head is the size of Garfield, who is in turn half as tall as Jon. I know the joke is bolstered by a big dog, but is some kind of Ice Age terror-dog necessary?