I followed the BB removal method suggested by the late, great Sheldon Brown (as demonstrated in the video below by RJ, skip to 6:11) and was able to remove the adjustable cup without damage.


Using a 6-inch long, 5/8" bolt with a 15/16" head and a corresponding nut, a 5-inch long, 21mm diameter pipe, and two flat washers on either side for the 5/8" bolt, a 1/2" impact wrench with a 15/16" socket, it took 15 seconds to get the adjustable cup out without damage. Inserted the bolt from drive side to non-drive side. After removal, the spindle and the inside of both cups look fine to me.

However, I noticed the threads on the fixed cup were stripped. It most likely came to me like that with the bike from the previous owner.