First: "Abortionist" is a word made up by right-wing fanatics. They use it to downplay the fact that abortion providers are doctors, often OB/GYNs. It would be like calling a dermitologist an "acne-ist." It doesn't really make sense, and there's already an actual term for what those doctors do. "Abortionist" is a loaded and totally incorrect word, and it's appalling to see it used over and over again in an article written by a supposedly pro-choice person.
Second: Tiller is not the pro-choice equivalent of Scott Roeder, and Saletan should be ashamed for suggesting as much.
Third: The headine "Is it wrong to murder an abortionist?" suggests that there's actually some debate amongst reasonable people on that issue. There is not.