The Danelectro can be a very tempermental instrument (doesn't like to stay in tune).
I bet he just didn't want to take any chances with this once-in-a-life-time gig.
The transperformance was used to great affect on the P/P unledded tour for going from Kashmir to Black Dog and back.
The b-bender is kind of like having a wammy bar but just for one string.
In this way, you can play a chord and then 'bend' one note while the rest of the chord remains intact. It kind of gives a pedal steel feeling.
It can be found on
All of My Love, Ozone Baby and I think Southbound Saurez.
As well as TYG live. Also when he played Layla at the ARMS show.
He used it much more live than on albums. But it was a telecatser with a b-bender.