I think the key here is that he said "finish a dive" solo. That's odd word choice. It's not they should be able to "dive solo" but "finish" a dive solo that presumably started with a buddy.This was an article in the newsletter years ago, where Jim Bram answered the question about solo certifications…it was his answer.
I don't know what he had in mind, but it could be as simple as immediately surface and end the dive. Or it could be finish the dive as planned without a buddy. That latter seems inconsistent with NAUI and PADI expectations.