Like "Attic Rat," I had a service call identical to that. If I "touch" an existing receptacle, it gets re-terminated on the terminal screws. They should be outlawed, it was designed for speed of...
Moisture area, and if somebody can install a sink there,somebody
will install a sink there.
"the extension cord used to supply this short piece of Type NM cable"
I believe that is a SO/SJO cord with a molded male cap rather than NM Type cable.