I stand corrected. Good catch. It might work anyway, but it's always better to get the right part if you have the choice.

One thing to note with "Shadow" rear derailleurs is that to use them with road shifters you need an inline barrel adjuster somewhere. Mountain bikes have an adjuster at the lever so it's not an issue, but with road shifters you have to bring your own. It's not a problem, but it is something to be aware of.