Thanks for the suggestions! None of them help, alas.
I keep the remove confirmation on at all times, I only enable expiration in wormhole and temp safe folders, and I already use temporary storage folders for permanent bookmarks because I organize them after creation into a bunch of shared folders. None of this prevents accidental deletions.
I don’t think an undo option (or as Posh Wynoa Spice suggested, a temporary Recycle Bin type arrangement) is an unreasonable request.