Here's the anti-climactic conclusion to this story. I took the two screws out and removed the plastic piece below that release button, and that allowed the button to be removed.


It was obvious that the protrusion was only necessary to keep the button round, and that it would function just the same being flat in front. Five minutes with the portable band saw + five more with the leatherman metal file later...


And when I reassembled and tried it, it now functions just fine and no longer interferes. Soon, I'll get some black paint (epoxy appliance enamel) and cover up the exposed aluminum.


As a final note:

At infinity focus, the 35mm Rodenstock Apo-Sironar Digital Lens needs to be close enough to the sensor that the rear element of the lens is inside the Panshot frame. When it's in that position, the ~59 1/2 mm outer diameter of the metal around the glass effectively prevents any linear movements.

Here's a link back.