Well, the content is now 100 years old, so that's an antique. But the print itself is most likely around 50 years old.
I'm not sure if sellers know that something needs to be at least 100 years old to be called an antique.
This seller has over 2,000 listings, mostly comic books, so he probably knows nothing about film. The other surprising thing is that he doesn't accept offers for this. I'm tempted to contact him to tell him he's off his rocker.
When I bought NOSFERATU this year, it was the first time I had actually seen the movie, actually. I was disappointed, however, in Blackhawk's print. The picture quality was excellent, but it apparently is missing much from the beginning. I had to check it out on youtube to see what I missed. They cut out (or I should say the pre-print that Blackhawk used was missing) all the scenes that explained Harker's motivation for going to Nosferatu's castle. It starts with him already at the inn in what I suppose is Transylvania. It is never explained that he is a real-estate agent who works for Renfield, and that he will be selling a house to the vampire.
Also, this print uses the more familiar names, like Harker, Renfield, and Mina, rather than the bogus names used when originally released in an attempt not to be sued by Bram Stoker (or his estate), which supposedly happened anyway -- and most prints were destroyed. Luckily some survived and what we can see on disc or on youtube is more or less complete -- certainly more complete than Blackhawk's print. Thunderbird's print is said to contain most of what's missing from the Blackhawk.
In any case, prints keep turning up regularly on eBay, and some apparently are not from Blackhawk, as evidenced by the lack of a Blackhawk box, as well as the number of reels -- which is more footage than Blackhawk had. Also, Blackhawk released even shorter versions, but according to the old catalogs, they considered this one pretty much "complete." Even their introductory titles on the film itself does not mention that there are missing pieces. I suppose 50+ years ago it was not well known that more complete prints were available, or that anything was missing at all from the Blackhawk.