It may be a rebuild, but it's still "new", in the sense that it will have perfect emissions. Provided, of course, that it's a *good* rebuild.
Rebuilt picture tubes used to be pretty common. Unfortunately, there is nobody left rebuilding them any more. Hawkeye might have been the last.
The thing that goes in most tubes is the gun assembly - the cathodes no longer emit enough electrons, and they get dim. Either that, or the gun fails or shorts. Screen burn is rather unique to video game and computer applications, however. In normal television use, it's pretty rare to wear out the phosphors or burn them. On color tubes, screen burn renders the tube unfit for a rebuild - there is no way to recoat the face of the glass with new phosphors after it's been assembled. Monochrome tubes can be recoated.
The basic process of a picture tube rebuild is to carefully let the tube up to air, cut the neck off, join a new neck and gun assembly on, pump it down/bake it, and seal it up.
So, it has no burn because nobody is going to rebuild a burnt tube. Also, remember that there are more applications for that tube than just WG6100 arcade monitors, it was used in some television sets as well. And, on top of that, there's no telling if the bell/face on that tube started life as a 19VLUP22 - it could theoretically have been some other 100 degree tube in a television set, which was rebuilt with the neck/gun assembly to make it a 19VLUP22.
-Ian