It seems my remark that confused you is that I indeed made a mistake about thinking Russell was a co-author on PAIP, which he is not. Although, I thought it was clear I was talking about AIMA and referring to PAIP in my parenthetical comment. I feel it's nicer to just ask a question rather than to say someone is confused.

I still think it's fair to say the book encourages the use of Python if one of the primary authors publishes solutions in that language over existing solutions in another language and the author promotes Python. Of course, it seems over time other languages have grown into providing solutions. I don't have the book (because of its exorbitant price) but do have PAIP, so I can't say for sure. Even the GitHub repo for the Lisp implementation says its out of date and was used back in 1995. This latter point is relevant and was what I was curious about. Were Norvig's comments referring to a time before the first edition was published, or was it after the first edition was published and sometime in between the first and second editions? I'm just generally curious about the context in which he's referring to.