How can Seth Macfarlane call himself a liberal?

As I understand it one of the key beliefs for liberals is that everyone is entitled to their own view, my question is how can he make fun of creationists? Though I am against abortion I can see how it infringes upon someone else's right to a choice but I don't see how creationism "restricts" someones ability to choice as long as it is an alternative to evolution not a replacement