I guess I'm really of the opinion that cemetaries are for the living. They're somewhere the loved ones of the deceased can come to terms with the death, and keep the feeling the deceased is still in one physical location (in addition to whatever spiritual location their religion suggests. We only treat cemetaries as "holy ground" because we know specific people were buried there - chances are, we are all right now on or near a site where a human being died some centuries ago - but since we don't know the people who died a thousand years ago, we don't worry about it.
I would definitely have a problem with a wedding in an *active* cemetary, where living people are still grieving the loss of friends and family members they loved, but an abandoned cemetary wouldn't bother me a bit. (Well, I wouldn't hold a wedding there, but I wouldn't have a problem with someone else doing so.)