The topics are already deleted, and I don’t have an estimate for when the user might request restoration of the topics, so I guess I can wait for bulk un-deletion to be implemented. I don’t think I’m the only one that would find it useful, there are quite a few posts here requesting help for doing so.
This also looks like a potentially easier and safer way to programmatically un-delete, assuming I can figure out how to generate the list of the user’s deleted topic IDs: