well, that Only include closed topics I actually read as "only include closed topics". It doesn't say anywhere that you only get open topics if you don't tink that setting.
I went ahead and did my move and while the topic list that was built didn't show locked topics, it did move them, but only after I did it a 2nd time by ticking that "closed topics" check box... I had duplicate topics after that run! Argh.
But due to another screw up on my part (I didn't delete the old topics) I was able to purge the target forum of the newly imported topics and now I'm about to start over.
I hestitate to say "bug" until I get some more experience with this function, but it sure smells like one.