I guess it's the same argument that was made earlier, in that there is a value in the Criminal Code's establishing standards of behaviour and telling people what behaviour we do and do not accept in Canada. By listing gender identity in that list, we are making a declaration, just as we made for the other groups.
Now, I understand that there are some people who don't like the hate crime section of the Criminal Code, and that's a debate for a different day. But if we are going to list groups, then I believe that gender identity is equally worthy of listing as any of the other groups that are already listed. You could make the same arguments, in essence, about several of the other things in the list: “Oh, we don't really need them there, because they'll be included.”
My argument is simply that equality for transgendered Canadians means listing and declaring in the same way we have for other factors in that list.