agreed ... also i think the dynamically-typed nature of python (and similar languages) makes them very amenable to rapid prototyping and experimentation (code just runs without having to fight the type inferencer or checker). python lets you do clean and beautiful functional programming, but also, as you mentioned, to drop down to quick-and-dirty imperative mode
the author has a good point about pure functional languages being better-suited for concurrent programming, though
Just to be clear, Clojure (and most lisps) are also dynamically typed and thus allow just the same experimental approach. Clojure and Common Lisp (I can't speak for other lisps, but I think some schemes too - PLT Scheme perhaps?) also have optional Type Hinting that allow the program to run quickly too.
the author has a good point about pure functional languages being better-suited for concurrent programming, though