Update! The keiki grew 2 shiny little leaves and the sat there for a while.
I read on the ob that you can goose along root formation by clumping up some wet sphagnum around the base of the keiki and keeping it wet. I gave it a try.
Nothing happened. Nothing. For a few months. Did the sphagnum clump dry out? Yeah. From time to time. But I faithfully re-wet the sphagnum clump every morning.
Then I gave up about a month or two ago. And now .....
Roots! Two tiny roots are starting to poke out.
Woot!!!
-Jason