Just like you have whole wheat bread it should be rye bread or call it white bread or regular, anything but rye, for the same price call it spelt?
Do they sprinkle spelt into it? I would say that the rye is what differentiates it from other breads, therefore that's how it got its name. Also it could be it used to actually be made out of rye. Same as lead pencils don't have any actual lead in them, but they kept the name...