I wonder just how accurately the folks at Michigan State could determine, back in 1886, which tomato varieties were no longer available. It's not like they could Google it.
By "available" did they mean in available in commercial trade? One could imagine many, many people continuing to grow a variety. Now whether or not they kept the name attached to it???
I think a lot of people were like Jesse's grandparents--they didn't know what the name was and they didn't care, as long as they got enough tomatoes for their needs.