Not at all. It's like half the other stuff in this forum - you have to decide for yourself whether it's out of copyright in your country or not. All the books in this forum are out of copyright somewhere, but not necessarily where you happen to live.
However, in the case of an obscure author such as Mr "Van Dine", that almost nobody today has ever heard of, the chances of anyone caring whether you download it in the "wrong" country are so small that, in practical terms, it's not worth worrying about.
In the case of better known stuff, where the US copyright holder is more likely to pursue people who upload to servers in the wrong country, we do now have an alternate server in Europe we can upload the books to, and just have a download link from here. These books really don't fall into that category, however!
Yes, you are absolutely correct. Technically speaking, if you live in the US, you shouldn't download this. It's for you to decide as an individual whether or not that matters to you.