I would probably come across as matching that description. So perhaps I can speak for that position a bit.

In this case I would not think re-assigning df as being in violation those principles. Might even be useful if it plays better with how the code interacts with debuggers and version control.

Its not really re-used in the sense that would motivate making up new names for the intermediate steps. It’s clearly just used as a syntactic aid for the operation chaining. So in my mind both expressions are equivalent from that perspective.

I would probably insist on limiting its scope to precisely that expression though, to maintain that obviousness.