Wondering: Is it possible for a file to be created after the first wildcard is interpreted, but before the second, so a file would get moved that wasn't catted?

Aside from being on Windows, he's also talking about thousands of files, so a shell might balk at that many anyway. That'd lead to using find, which done right should eliminate any concerns about moving unprocessed files.

Yes, yes, and yes.

You get my ++ upvote across the board. My reply was hasty and without caffeine.