Thanks for the responses.
Here's what happened. A few hours after I posted this note, I noticed that the disk activity had finally dropped off, and it no longer seemed to be doing anything much. The computer seemed to be responding normally.
The account, however, was still labeled as being deleted.
I figured that was enough of that, however, and closed the systems preferences window/application. It had to be force-quit, since it complained that it was still 'deleting a user account', but nothing bad seemed to happen. I immediately restarted system preferences. The offending account was still there, but without the 'deleting account' label.
I deleted it again, but this time opted for the simple 'delete immediately' option. This worked as advertised, and immediately.
Now, everything is working properly.
So, my conclusion is –– stick to the basic 'delete account' option, if possible, and be prepared for a long wait if you opt for the others. It does, however, look like you can interrupt this process without causing any problems.