Not when it's the use of a registered trademark for commercial purposes without the consent of the trademark owner, it's not. The guy is not trying to make a political statement; he is trying to make a profit. That changes EVERYTHING.
Besides, any trademark violation can be turned into a "political" arguement; all the violator has to do is make some outlandish (and even blatantly false) claim about how the company whose trademark he's stolen is somehow "making kids work in sweatshops in China for 30 cents a day," or perhaps "doesn't pay women the same salaries it pays men," and voila, suddenly it's "protected speech?" Horsepuckey. The courts aren't that stupid.
O'Reilly is a different case. He's fair game in terms of what the shirt depicts.
O'Reilly's fair game, but that shirt too includes a giant depiction of what is obviously a completely unadulterated FNC logo. I don't know whether the courts will allow it just because the shirt is designed so that you can't see the word "Fox" in it.
In the end, the O'Reilly shirt doesn't matter anyway. The damages for the "Faux News" shirt alone will bankrupt this guy.