Bruce, the first sentence of the first post says:

"I recently was asked by a client about a guitar that would accommodate his missing ring and little finger on his chording hand."

So, he's got a thumb plus two more fingers, index and middle.

Dind't Django Rhinehart have a couple of left-hand fingers cut off, or maybe cut short? He was, of coure, an exceptional guitarist, and I believe he even played in standard tuning.

Not that we could, or should, expect anyone be another Django...

Jerry Garcia lost a finger when he was young, but that was on his right hand ~ not nearly as big an issue.