it's just a shitty racist (sorry, xenophobic) cartoon instead of some grand defence of freedom of expression
Maybe it's both.
First, I didn't draw it, just reposted it.
Second, you realize that that's actually how free speech is supposed to work, right? I can say whatever I like. The flip side is, you can respond too. For example, you could respond by drawing a cartoon of Richard Dawkins and Christopher Hitchens in a sixty nine while also eating a baby. Or draw me and my Mom both getting raped by Satan or something. Whatever. It's all good!
The idea of freedom of expression isn't that HURR DERP I CAN SAY WHATEVER I WANT IM SO COOL I CAN OFFEND PEOPLE. The idea is that a society can discuss and explore and argue their way through any idea, no matter how bizarre or stupid or ugly or noble, and work out if the idea or argument is good or not, without fear of being burned at a stake or something for merely making a suggestion that might just benefit all of society. Or it might be a stupid idea, but you should be free to discuss it, period.
For example, I believe that if you want to stand up and say that, I dunno... it should be legal to marry with a child, let's say. I might be aghast and throw up or whatever, but I'd want to hear you out. Do you have any good reasons why this should be legalized? Can you make any reasonable arguments for it? Others could then disagree and explain all the many good reasons why no, you shouldn't be allowed to marry a child. If you can't come up with good counter-arguments or make any good points, the idea is dismissed.
This is why racists don't go about openly broadcasting their bigotry and prejudice, but only do it in racist forums among other racists, or use code language to mask their hatred. Because they know that even though they have the freedom to, they'd be shouted down and mocked and derided. Freedom of speech / expression work both ways.
And then, of course, there's humor, satire, parody. Even if in very bad taste, it needs to be allowed.
And by the way, I thought all the Charlie Hebdo cartoons were generally shitty. But it was shittier to kill them in the name of god, wasn't it? Yes? Then we agree on pretty much everything, except that I didn't draw the cartoon myself.