Follow up just in case someone is wondering how to get the body off. I still don’t know!
Turned out I did not need to remove the shell. When looking at the loco I realized that the cab windows were modeled halfway open. So even though the figure was upside down and backward, I was able to use fine point modeling tweezers to maneuver him back into position where a small dap of glue kept him seated.
Two observations of interest. The figure itself is not styrene or ABS, but a soft flexible vinyl-like material. So you need a multi purpose cement for glue. Also, the figure is very poorly painted! My main hobby is painting military miniatures for gaming, so it was really apparent to me how poorly he was painted. But, the paint job is definitely “good enough” for what little you can see of him, so I left it. But had I opened the body and had full access to the figure, I think an hour at the paint table would have produced a fine looking engineer.