I wouldn’t call them vultures. If the house had to be torn down anyway, why NOT save parts of it that are of some architectural value? Folks love being able to re-use mantels, moldings, doors, floors, that came from old homes. It would be silly to trash them.
Particularly if parts of a house come from a famous author. Some people take pride in owning something that belonged to a famous personage.
$250,000 for a postcard, not even written by the famous man in question? Puh-lease. The man is (hopefully) deluding himself.