I tend to agree that later scavenging is more likely, even much more likely, but wouldn't completely rule out the first possibility.
At some point after those trees were cut, this stand of trees was entirely forgotten. So one way or another, it happened a long time ago.
Presumably there are some clues elsewhere in the area. I'm thinking buildings, carvings, furniture etc. made with the scavenged wood, whether extant or buried/ruined. If they were cut less than, say, 500 years ago I'd expect it to be possible (which is not to say easy) to find some of the wood still in use somewhere.