The anecdote proves nothing because the model could potentially have known of the McGonagal character without ever being trained on the books, since that character appears in a lot of fan fiction. So their point is invalid and their anecdote proves nothing.

I’m having a hard time envisioning a situation where testing my code requires a bunch of unused variables. Just don’t declare the variables until you’ve started writing the code that uses them…

Why in the world would you want to develop something that doesn’t follow the coding rules required by your org, just so you can go back and fix everything before submitting a PR? That’s just extra work.